diff --git a/src/lib/components/SubmissionStatus/UpdatingDropdown.svelte b/src/lib/components/SubmissionStatus/UpdatingDropdown.svelte
new file mode 100644
index 000000000..6b286cd96
--- /dev/null
+++ b/src/lib/components/SubmissionStatus/UpdatingDropdown.svelte
@@ -0,0 +1,228 @@
+<!-- Usage
+// Script
+<script lang="ts">
+  import type { TaskResult } from '$lib/types/task';
+
+  import UpdatingDropdown from '$lib/components/SubmissionStatus/UpdatingDropdown.svelte';
+
+  interface Props {
+    taskResult: TaskResult;
+    isLoggedIn: boolean;
+    onupdate?: (updatedTask: TaskResult) => void;
+  }
+
+  let { taskResult, isLoggedIn, onupdate = () => {} }: Props = $props();
+
+  let updatingDropdown: UpdatingDropdown;
+</script>
+
+
+// Component
+<button
+  type="button"
+  onclick={() => updatingDropdown.toggle()} // Open / close the dropdown.
+>
+
+<UpdatingDropdown bind:this={updatingDropdown} {taskResult} {isLoggedIn} {onupdate} />
+-->
+<script lang="ts">
+  import { getStores } from '$app/stores';
+  import { enhance } from '$app/forms';
+
+  import { Dropdown, DropdownUl, DropdownLi, uiHelpers } from 'svelte-5-ui-lib';
+
+  import type { TaskResult } from '$lib/types/task';
+
+  import InputFieldWrapper from '$lib/components/InputFieldWrapper.svelte';
+
+  import { submission_statuses } from '$lib/services/submission_status';
+  import { errorMessageStore } from '$lib/stores/error_message';
+
+  import { SIGNUP_PAGE, LOGIN_PAGE } from '$lib/constants/navbar-links';
+
+  interface Props {
+    taskResult: TaskResult;
+    isLoggedIn: boolean;
+    onupdate: (updatedTask: TaskResult) => void; // Ensure to update task result in parent component.
+  }
+
+  let { taskResult, isLoggedIn, onupdate }: Props = $props();
+
+  const { page } = getStores();
+  let activeUrl = $state($page.url.pathname);
+
+  let dropdown = uiHelpers();
+  let dropdownStatus = $state(false);
+  let closeDropdown = dropdown.close;
+
+  $effect(() => {
+    activeUrl = $page.url.pathname;
+    dropdownStatus = dropdown.isOpen;
+  });
+
+  export function toggle(): void {
+    dropdown.toggle();
+  }
+
+  let selectedSubmissionStatus = $state<SubmissionStatus>();
+  let showForm = $state(false);
+
+  function handleClick(submissionStatus: {
+    innerId: string;
+    innerName: string;
+    labelName: string;
+  }): void {
+    selectedSubmissionStatus = submissionStatus;
+    showForm = true;
+
+    // Submit after the form is rendered.
+    setTimeout(() => {
+      const submitButton = document.querySelector(
+        '#submissionStatusForm button[type="submit"]',
+      ) as HTMLButtonElement;
+
+      if (submitButton) {
+        // Submit the form via the enhance directive by clicking the button.
+        submitButton.click();
+      }
+    }, 10);
+  }
+
+  type SubmissionStatus = {
+    innerId: string;
+    innerName: string;
+    labelName: string;
+  };
+
+  type EnhanceForSubmit = {
+    formData: FormData;
+    action: URL;
+    cancel: () => void;
+  };
+
+  const FAILED_TO_UPDATE_SUBMISSION_STATUS =
+    '回答状況の更新に失敗しました。もう一度試してください。';
+
+  const handleSubmit = (submissionStatus: SubmissionStatus) => {
+    return ({ formData, action, cancel }: EnhanceForSubmit) => {
+      // Cancel the default form submission.
+      cancel();
+
+      if (isSame(submissionStatus, taskResult)) {
+        console.log('Skipping: Submission status already set to', submissionStatus.labelName);
+
+        resetDropdown();
+        return () => {};
+      }
+
+      // Submit data manually using fetch API.
+      fetch(action, {
+        method: 'POST',
+        body: formData,
+        headers: {
+          Accept: 'application/json',
+        },
+      })
+        .then((response) => response.json())
+        .then(() => {
+          const updatedTaskResult = updateTaskResult(taskResult, submissionStatus);
+          onupdate(updatedTaskResult);
+        })
+        .catch((error) => {
+          console.error('Failed to update submission status: ', error);
+          errorMessageStore.setAndClearAfterTimeout(FAILED_TO_UPDATE_SUBMISSION_STATUS, 10000);
+        })
+        .finally(() => {
+          resetDropdown();
+        });
+
+      // Do not change anything in SvelteKit.
+      return () => {};
+    };
+  };
+
+  function isSame(submissionStatus: SubmissionStatus, taskResult: TaskResult): boolean {
+    return submissionStatus.innerName === taskResult.status_name;
+  }
+
+  function resetDropdown(): void {
+    closeDropdown();
+    showForm = false;
+  }
+
+  function updateTaskResult(
+    taskResult: TaskResult,
+    submissionStatus: SubmissionStatus,
+  ): TaskResult {
+    return {
+      ...taskResult,
+      status_name: submissionStatus.innerName,
+      status_id: submissionStatus.innerId,
+      submission_status_label_name: submissionStatus.labelName,
+      is_ac: submissionStatus.innerName === 'ac',
+      updated_at: new Date(),
+    };
+  }
+
+  // TODO: When customizing submission status, implement DB fetching for status options.
+  const submissionStatusOptions = submission_statuses.map((status) => {
+    const option = {
+      innerId: status.id,
+      innerName: status.status_name,
+      labelName: status.label_name,
+    };
+    return option;
+  });
+</script>
+
+<div class="relative">
+  <Dropdown
+    {activeUrl}
+    {dropdownStatus}
+    {closeDropdown}
+    class="absolute w-32 z-20 left-auto right-0 mt-8"
+  >
+    <DropdownUl>
+      {#if isLoggedIn}
+        {#each submissionStatusOptions as submissionStatus}
+          <DropdownLi href="javascript:void(0)" onclick={() => handleClick(submissionStatus)}>
+            {submissionStatus.labelName}
+          </DropdownLi>
+        {/each}
+      {:else}
+        <DropdownLi href={SIGNUP_PAGE}>アカウント作成</DropdownLi>
+        <DropdownLi href={LOGIN_PAGE}>ログイン</DropdownLi>
+      {/if}
+    </DropdownUl>
+  </Dropdown>
+
+  {#if showForm && selectedSubmissionStatus}
+    {@render submissionStatusForm(taskResult, selectedSubmissionStatus)}
+  {/if}
+</div>
+
+{#snippet submissionStatusForm(selectedTaskResult: TaskResult, submissionStatus: SubmissionStatus)}
+  <form
+    id="submissionStatusForm"
+    method="POST"
+    action="?/update"
+    style="display:none;"
+    use:enhance={handleSubmit(submissionStatus)}
+  >
+    <!-- Task id -->
+    <InputFieldWrapper
+      inputFieldType="hidden"
+      inputFieldName="taskId"
+      inputValue={selectedTaskResult.task_id}
+    />
+
+    <!-- Submission status -->
+    <InputFieldWrapper
+      inputFieldType="hidden"
+      inputFieldName="submissionStatus"
+      inputValue={submissionStatus.innerName}
+    />
+
+    <button type="submit">Submit</button>
+  </form>
+{/snippet}
diff --git a/src/lib/components/TaskTables/TaskTable.svelte b/src/lib/components/TaskTables/TaskTable.svelte
index daf2e5596..d7b304d70 100644
--- a/src/lib/components/TaskTables/TaskTable.svelte
+++ b/src/lib/components/TaskTables/TaskTable.svelte
@@ -14,7 +14,6 @@
   import type { TaskResults, TaskResult } from '$lib/types/task';
   import type { ContestTableProvider } from '$lib/types/contest_table_provider';
 
-  import UpdatingModal from '$lib/components/SubmissionStatus/UpdatingModal.svelte';
   import TaskTableBodyCell from '$lib/components/TaskTables/TaskTableBodyCell.svelte';
 
   import {
@@ -31,6 +30,7 @@
 
   let { taskResults, isLoggedIn }: Props = $props();
 
+  // Prepare contest table provider based on the active contest type.
   let activeContestType = $state<ContestTableProviders>('abcLatest20Rounds');
 
   let provider: ContestTableProvider = $derived(
@@ -52,20 +52,8 @@
     return provider.getContestRoundLabel(contestId);
   }
 
-  let updatingModal: UpdatingModal | null = null;
-
-  // WHY: () => updatingModal.openModal(taskResult) だけだと、updatingModalがnullの可能性があるため。
-  function openModal(taskResult: TaskResult): void {
-    if (updatingModal) {
-      updatingModal.openModal(taskResult);
-    } else {
-      console.error('Failed to initialize UpdatingModal component.');
-    }
-  }
-
   function getBodyCellClasses(contestId: string, taskIndex: string): string {
-    const baseClasses =
-      'w-1/2 xs:w-1/3 sm:w-1/4 md:w-1/5 lg:w-1/6 px-1 py-1 border hover:brightness-125 transition-all';
+    const baseClasses = 'w-1/2 xs:w-1/3 sm:w-1/4 md:w-1/5 lg:w-1/6 px-1 py-1 border';
     const backgroundColor = getBackgroundColor(taskTable[contestId][taskIndex]);
 
     return `${baseClasses} ${backgroundColor}`;
@@ -80,6 +68,43 @@
 
     return '';
   }
+
+  // Update task results dynamically.
+  // Computational complexity of preparation table: O(N), where N is the number of task results.
+  let taskResultsMap = $derived(() => {
+    return taskResults.reduce((map: Map<string, TaskResult>, taskResult: TaskResult) => {
+      if (!map.has(taskResult.task_id)) {
+        map.set(taskResult.task_id, taskResult);
+      }
+      return map;
+    }, new Map<string, TaskResult>());
+  });
+
+  let taskIndicesMap = $derived(() => {
+    const indices = new Map<string, number>();
+
+    taskResults.forEach((task, index) => {
+      indices.set(task.task_id, index);
+    });
+
+    return indices;
+  });
+
+  function handleUpdateTaskResult(updatedTask: TaskResult): void {
+    const map = taskResultsMap();
+
+    if (map.has(updatedTask.task_id)) {
+      map.set(updatedTask.task_id, updatedTask);
+    }
+
+    const index = taskIndicesMap().get(updatedTask.task_id);
+
+    if (index !== undefined) {
+      const newTaskResults = [...taskResults];
+      newTaskResults[index] = updatedTask;
+      taskResults = newTaskResults;
+    }
+  }
 </script>
 
 <!-- See: -->
@@ -117,8 +142,9 @@
 
         {#if taskTableHeaderIds.length}
           {#each taskTableHeaderIds as taskTableHeaderId}
-            <TableHeadCell class="text-center border" scope="col">{taskTableHeaderId}</TableHeadCell
-            >
+            <TableHeadCell class="text-center border" scope="col">
+              {taskTableHeaderId}
+            </TableHeadCell>
           {/each}
         {/if}
       </TableHead>
@@ -140,7 +166,7 @@
                     <TaskTableBodyCell
                       taskResult={taskTable[contestId][taskTableHeaderId]}
                       {isLoggedIn}
-                      onClick={() => openModal(taskTable[contestId][taskTableHeaderId])}
+                      onupdate={(updatedTask: TaskResult) => handleUpdateTaskResult(updatedTask)}
                     />
                   {/if}
                 </TableBodyCell>
@@ -152,5 +178,3 @@
     </Table>
   </div>
 </div>
-
-<UpdatingModal bind:this={updatingModal} {isLoggedIn} />
diff --git a/src/lib/components/TaskTables/TaskTableBodyCell.svelte b/src/lib/components/TaskTables/TaskTableBodyCell.svelte
index c7bd2c67b..5ae8e1e4b 100644
--- a/src/lib/components/TaskTables/TaskTableBodyCell.svelte
+++ b/src/lib/components/TaskTables/TaskTableBodyCell.svelte
@@ -3,18 +3,21 @@
 
   import type { TaskResult } from '$lib/types/task';
 
-  import ExternalLinkWrapper from '$lib/components/ExternalLinkWrapper.svelte';
   import GradeLabel from '$lib/components/GradeLabel.svelte';
+  import ExternalLinkWrapper from '$lib/components/ExternalLinkWrapper.svelte';
+  import UpdatingDropdown from '$lib/components/SubmissionStatus/UpdatingDropdown.svelte';
 
   import { getTaskUrl, removeTaskIndexFromTitle } from '$lib/utils/task';
 
   interface Props {
     taskResult: TaskResult;
     isLoggedIn: boolean;
-    onClick: () => void;
+    onupdate?: (updatedTask: TaskResult) => void; // Ensure to update task result in parent component.
   }
 
-  let { taskResult, isLoggedIn, onClick }: Props = $props();
+  let { taskResult, isLoggedIn, onupdate = () => {} }: Props = $props();
+
+  let updatingDropdown: UpdatingDropdown;
 </script>
 
 <div class="flex items-center w-full space-x-1 text-left text-sm sm:text-md">
@@ -22,10 +25,7 @@
 
   <div class="flex justify-between w-full min-w-0">
     {@render taskTitleAndExternalLink(taskResult)}
-
-    {#if isLoggedIn}
-      {@render submissionUpdaterAndLinksOfTaskDetailPage(onClick, taskResult)}
-    {/if}
+    {@render submissionUpdaterAndLinksOfTaskDetailPage(taskResult)}
   </div>
 </div>
 
@@ -52,13 +52,19 @@
   </div>
 {/snippet}
 
-{#snippet submissionUpdaterAndLinksOfTaskDetailPage(onClick: () => void, taskResult: TaskResult)}
-  <button
-    type="button"
-    class="flex-shrink-0 w-6 ml-auto"
-    onclick={onClick}
-    aria-label="Update submission for {taskResult.title}"
-  >
-    <EllipsisVertical class="w-4 h-4 mx-auto" />
-  </button>
+<!-- See: -->
+<!-- https://svelte-5-ui-lib.codewithshin.com/components/dropdown -->
+{#snippet submissionUpdaterAndLinksOfTaskDetailPage(selectedTaskResult: TaskResult)}
+  <div class="flex items-start justify-center">
+    <button
+      type="button"
+      class="flex-shrink-0 w-6 ml-auto"
+      onclick={() => updatingDropdown.toggle()}
+      aria-label="Update submission for {selectedTaskResult.title}"
+    >
+      <EllipsisVertical class="w-4 h-4 mx-auto" />
+    </button>
+
+    <UpdatingDropdown bind:this={updatingDropdown} {taskResult} {isLoggedIn} {onupdate} />
+  </div>
 {/snippet}