diff --git a/CHANGELOG-Japanese.md b/CHANGELOG-Japanese.md
index 87180caa..e9398d53 100644
--- a/CHANGELOG-Japanese.md
+++ b/CHANGELOG-Japanese.md
@@ -11,6 +11,7 @@
 - 結果概要に各レベルで検知した上位5つのルールを表示するようにした。 (#667) (@hitenkoku)
 - 結果概要を出力しないようにするために `--no-summary` オプションを追加した。 (#672) (@hitenkoku)
 - 結果概要の表示を短縮させた。 (#675 #678) (@hitenkoku)
+- channel_abbreviations.txtによるChannelフィールドのチェックを大文字小文字の区別をなくした。 (#685) (@hitenkoku)
 
 **バグ修正:**
 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4b02f742..cd145245 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@
 - Added top alerts to results summary. (#667) (@hitenkoku)
 - Added `--no-summary` option to not display the results summary. (#672) (@hitenkoku)
 - Made the results summary more compact. (#675 #678) (@hitenkoku)
+- Made Channel field in channel_abbreviations.txt case-insensitive. (#685) (@hitenkoku)
 
 **Bug Fixes:**
 
diff --git a/src/afterfact.rs b/src/afterfact.rs
index 076e5578..4bf61ee6 100644
--- a/src/afterfact.rs
+++ b/src/afterfact.rs
@@ -795,7 +795,7 @@ mod tests {
                 (
                     "%Channel%".to_owned(),
                     mock_ch_filter
-                        .get("Security")
+                        .get(&"Security".to_ascii_lowercase())
                         .unwrap_or(&String::default())
                         .to_string(),
                 ),
diff --git a/src/detections/detection.rs b/src/detections/detection.rs
index 2f4e6207..75e801de 100644
--- a/src/detections/detection.rs
+++ b/src/detections/detection.rs
@@ -264,7 +264,10 @@ impl Detection {
                     "%Channel%" => {
                         profile_converter.insert(
                             "%Channel%".to_string(),
-                            CH_CONFIG.get(ch_str).unwrap_or(ch_str).to_string(),
+                            CH_CONFIG
+                                .get(&ch_str.to_ascii_lowercase())
+                                .unwrap_or(ch_str)
+                                .to_string(),
                         );
                     }
                     "%Level%" => {
diff --git a/src/detections/message.rs b/src/detections/message.rs
index e3a3d235..fa374282 100644
--- a/src/detections/message.rs
+++ b/src/detections/message.rs
@@ -105,10 +105,10 @@ pub fn create_output_filter_config(path: &str) -> HashMap<String, String> {
             return;
         }
 
-        let tag_full_str = line[0].trim();
+        let tag_full_str = line[0].trim().to_ascii_lowercase();
         let tag_replace_str = line[1].trim();
 
-        ret.insert(tag_full_str.to_owned(), tag_replace_str.to_owned());
+        ret.insert(tag_full_str, tag_replace_str.to_owned());
     });
     ret
 }
@@ -599,7 +599,7 @@ mod tests {
         let actual = create_output_filter_config("test_files/config/channel_abbreviations.txt");
         let actual2 = create_output_filter_config("test_files/config/channel_abbreviations.txt");
         let expected: HashMap<String, String> = HashMap::from([
-            ("Security".to_string(), "Sec".to_string()),
+            ("Security".to_ascii_lowercase(), "Sec".to_string()),
             ("xxx".to_string(), "yyy".to_string()),
         ]);
         _check_hashmap_element(&expected, actual);