diff --git a/orderedmap.go b/orderedmap.go
index 61587d9..8ac17a6 100644
--- a/orderedmap.go
+++ b/orderedmap.go
@@ -242,24 +242,40 @@ func decodeSlice(dec *json.Decoder, s []interface{}, escapeHTML bool) error {
 	}
 }
 
+func encodeNoNewline(v interface{}, escapeHTML bool) ([]byte, error) {
+	var buf bytes.Buffer
+	enc := json.NewEncoder(&buf)
+	enc.SetEscapeHTML(escapeHTML)
+	if err := enc.Encode(v); err != nil {
+		return nil, err
+	}
+	// 末尾の改行（'\n'）を削除
+	data := buf.Bytes()
+	if len(data) > 0 && data[len(data)-1] == '\n' {
+		data = data[:len(data)-1]
+	}
+	return data, nil
+}
+
 func (o OrderedMap) MarshalJSON() ([]byte, error) {
 	var buf bytes.Buffer
 	buf.WriteByte('{')
-	encoder := json.NewEncoder(&buf)
-	encoder.SetEscapeHTML(o.escapeHTML)
 	for i, k := range o.keys {
 		if i > 0 {
 			buf.WriteByte(',')
 		}
-		// add key
-		if err := encoder.Encode(k); err != nil {
+		keyBytes, err := encodeNoNewline(k, o.escapeHTML)
+		if err != nil {
 			return nil, err
 		}
+		buf.Write(keyBytes)
 		buf.WriteByte(':')
-		// add value
-		if err := encoder.Encode(o.values[k]); err != nil {
+
+		valueBytes, err := encodeNoNewline(o.values[k], o.escapeHTML)
+		if err != nil {
 			return nil, err
 		}
+		buf.Write(valueBytes)
 	}
 	buf.WriteByte('}')
 	return buf.Bytes(), nil
diff --git a/orderedmap_test.go b/orderedmap_test.go
index 5b89ef6..6e895c2 100644
--- a/orderedmap_test.go
+++ b/orderedmap_test.go
@@ -69,10 +69,10 @@ func TestOrderedMap(t *testing.T) {
 	// Values method
 	values := o.Values()
 	expectedValues := map[string]interface{}{
-		"number": 4,
-		"string": "x",
+		"number":  4,
+		"string":  "x",
 		"strings": []string{"t", "u"},
-		"mixed": []interface{}{ 1, "1" },
+		"mixed":   []interface{}{1, "1"},
 	}
 	if !reflect.DeepEqual(values, expectedValues) {
 		t.Error("Values method returned unexpected map")
@@ -595,3 +595,29 @@ func TestOrderedMap_empty_map(t *testing.T) {
 		t.Error("Got", marshalledStr)
 	}
 }
+
+func TestEncodeNoNewline(t *testing.T) {
+	tests := []struct {
+		input      interface{}
+		escapeHTML bool
+		expected   string
+	}{
+		{"test", true, "\"test\""},
+		{"<>&", false, "\"<>&\""},
+		{"<>&", true, "\"\\u003c\\u003e\\u0026\""},
+		{123, true, "123"},
+	}
+
+	for _, tt := range tests {
+		b, err := encodeNoNewline(tt.input, tt.escapeHTML)
+		if err != nil {
+			t.Errorf("encodeNoNewline error: %v", err)
+		}
+		if len(b) > 0 && b[len(b)-1] == '\n' {
+			t.Errorf("encodeNoNewline output ends with newline: %q", string(b))
+		}
+		if string(b) != tt.expected {
+			t.Errorf("For input %v with escapeHTML=%v: expected %q, got %q", tt.input, tt.escapeHTML, tt.expected, string(b))
+		}
+	}
+}