diff --git a/.github/workflows/auto-testing.yml b/.github/workflows/auto-testing.yml
index 351372b0..67a2166d 100644
--- a/.github/workflows/auto-testing.yml
+++ b/.github/workflows/auto-testing.yml
@@ -17,7 +17,6 @@ jobs:
     strategy:
       matrix:
         python-version:
-          - '3.9'
           - '3.10'
           - '3.11'
           - '3.12'
@@ -53,7 +52,6 @@ jobs:
     strategy:
       matrix:
         python-version:
-          - '3.9'
           - '3.10'
           - '3.11'
           - '3.12'
diff --git a/README.rst b/README.rst
index 1c9dae4f..cf147071 100644
--- a/README.rst
+++ b/README.rst
@@ -22,7 +22,7 @@ Japanese: https://developers.line.biz/ja/docs/messaging-api/overview/
 Requirements
 ------------
 
--  Python >= 3.9
+-  Python >= 3.10
 
 Installation
 ------------
diff --git a/generator/src/main/java/line/bot/generator/PythonNextgenCustomClientGenerator.java b/generator/src/main/java/line/bot/generator/PythonNextgenCustomClientGenerator.java
index 30a3bf5b..b5a4f040 100644
--- a/generator/src/main/java/line/bot/generator/PythonNextgenCustomClientGenerator.java
+++ b/generator/src/main/java/line/bot/generator/PythonNextgenCustomClientGenerator.java
@@ -1545,7 +1545,7 @@ public String generatePackageName(String packageName) {
 
     @Override
     public String generatorLanguageVersion() {
-        return "3.9+";
+        return "3.10+";
     }
 
     @Override
diff --git a/generator/src/main/resources/python-nextgen-custom-client/github-workflow.mustache b/generator/src/main/resources/python-nextgen-custom-client/github-workflow.mustache
index 8b15b1d0..89c5d628 100644
--- a/generator/src/main/resources/python-nextgen-custom-client/github-workflow.mustache
+++ b/generator/src/main/resources/python-nextgen-custom-client/github-workflow.mustache
@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.9", "3.10"]
+        python-version: ["3.10"]
 
     steps:
       - uses: actions/checkout@v3
diff --git a/generator/src/main/resources/python-nextgen-custom-client/pyproject.mustache b/generator/src/main/resources/python-nextgen-custom-client/pyproject.mustache
index 2ba98715..726b08b9 100644
--- a/generator/src/main/resources/python-nextgen-custom-client/pyproject.mustache
+++ b/generator/src/main/resources/python-nextgen-custom-client/pyproject.mustache
@@ -9,7 +9,7 @@ repository = "https://github.com/{{{gitRepoId}}}/{{{gitUserId}}}"
 keywords = ["OpenAPI", "OpenAPI-Generator", "{{{appName}}}"]
 
 [tool.poetry.dependencies]
-python = "^3.9"
+python = "^3.10"
 
 urllib3 = ">= 1.25.3"
 python-dateutil = ">=2.8.2"
@@ -21,14 +21,14 @@ tornado = ">=4.2,<5"
 {{/tornado}}
 {{#hasHttpSignatureMethods}}
 pem = ">= 19.3.0"
-pycryptodome = ">= 3.9.0"
+pycryptodome = ">= 3.10.0"
 {{/hasHttpSignatureMethods}}
 pydantic = "^1.10.5, <2"
 aenum = ">=3.1.11"
 
 [tool.poetry.dev-dependencies]
 pytest = ">=7.2.1"
-tox = ">=3.9.0"
+tox = ">=3.10.0"
 flake8 = ">=4.0.0"
 
 [build-system]
diff --git a/generator/src/main/resources/python-nextgen-custom-client/setup.mustache b/generator/src/main/resources/python-nextgen-custom-client/setup.mustache
index 849bdec3..254f442c 100644
--- a/generator/src/main/resources/python-nextgen-custom-client/setup.mustache
+++ b/generator/src/main/resources/python-nextgen-custom-client/setup.mustache
@@ -12,7 +12,7 @@ from setuptools import setup, find_packages  # noqa: H301
 # http://pypi.python.org/pypi/setuptools
 NAME = "{{{projectName}}}"
 VERSION = "{{packageVersion}}"
-PYTHON_REQUIRES = ">=3.9"
+PYTHON_REQUIRES = ">=3.10"
 {{#apiInfo}}
 {{#apis}}
 {{#-last}}
@@ -27,7 +27,7 @@ REQUIRES = [
 {{/tornado}}
 {{#hasHttpSignatureMethods}}
     "pem>=19.3.0",
-    "pycryptodome>=3.9.0",
+    "pycryptodome>=3.10.0",
 {{/hasHttpSignatureMethods}}
     "pydantic >= 1.10.5, < 2",
     "aenum"
diff --git a/setup.py b/setup.py
index dea57af0..f58200bb 100644
--- a/setup.py
+++ b/setup.py
@@ -188,7 +188,7 @@ def run(self):
     long_description=long_description,
     license='Apache License 2.0',
     packages=find_packages(include=["linebot*"]),
-    python_requires=">=3.9.0",
+    python_requires=">=3.10.0",
     install_requires=_requirements(),
     tests_require=_requirements_test(),
     cmdclass={
@@ -200,7 +200,6 @@ def run(self):
         "License :: OSI Approved :: Apache Software License",
         "Intended Audience :: Developers",
         "Programming Language :: Python",
-        "Programming Language :: Python :: 3.9",
         "Programming Language :: Python :: 3.10",
         "Programming Language :: Python :: 3.11",
         "Programming Language :: Python :: 3.12",
diff --git a/tox.ini b/tox.ini
index fd037010..8d3f39cf 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,5 @@
 [tox]
 envlist =
-    py3.9,
     py3.10,
     py3.11,
     py3.12,