diff --git a/stationapi/src/domain/ipa.rs b/stationapi/src/domain/ipa.rs
index 4b16f0b7..1c204954 100644
--- a/stationapi/src/domain/ipa.rs
+++ b/stationapi/src/domain/ipa.rs
@@ -1,3 +1,27 @@
+/// Common katakana suffixes for line names, ordered longest-first for greedy matching.
+const LINE_NAME_SUFFIXES: &[&str] = &["ホンセン", "シセン", "セン"];
+/// Suffixes that should NOT be stripped even though they end with セン.
+const LINE_NAME_SUFFIX_EXCEPTIONS: &[&str] = &["シンカンセン"];
+
+/// Strip a common line-name suffix (線/本線/支線) from a katakana string.
+/// 新幹線 (Shinkansen) is preserved as it is used as-is in English.
+/// Returns the stem (without the suffix). If no known suffix is found, returns the input unchanged.
+pub fn strip_line_name_suffix(input: &str) -> &str {
+    for exception in LINE_NAME_SUFFIX_EXCEPTIONS {
+        if input.ends_with(exception) {
+            return input;
+        }
+    }
+    for suffix in LINE_NAME_SUFFIXES {
+        if let Some(stem) = input.strip_suffix(suffix) {
+            if !stem.is_empty() {
+                return stem;
+            }
+        }
+    }
+    input
+}
+
 /// Convert a katakana string to its IPA transcription.
 /// Returns `None` if the input contains characters that cannot be converted.
 pub fn katakana_to_ipa(input: &str) -> Option<String> {
@@ -608,4 +632,56 @@ mod tests {
             "dokkʲoːdaiɡakɯmae soːkamat͡sɯbaɾa"
         );
     }
+
+    // ============================================
+    // strip_line_name_suffix tests
+    // ============================================
+
+    #[test]
+    fn test_strip_sen() {
+        assert_eq!(
+            strip_line_name_suffix("セイブイケブクロセン"),
+            "セイブイケブクロ"
+        );
+    }
+
+    #[test]
+    fn test_strip_honsen() {
+        assert_eq!(
+            strip_line_name_suffix("トウカイドウホンセン"),
+            "トウカイドウ"
+        );
+    }
+
+    #[test]
+    fn test_strip_shinkansen_preserved() {
+        // 新幹線(Shinkansen)は英語でもそのまま使われるので除去しない
+        assert_eq!(
+            strip_line_name_suffix("トウホクシンカンセン"),
+            "トウホクシンカンセン"
+        );
+    }
+
+    #[test]
+    fn test_strip_shisen() {
+        assert_eq!(
+            strip_line_name_suffix("ナガノハラクサツグチシセン"),
+            "ナガノハラクサツグチ"
+        );
+    }
+
+    #[test]
+    fn test_strip_no_suffix() {
+        // ライン等セン以外の末尾はそのまま返す
+        assert_eq!(
+            strip_line_name_suffix("ショウナンシンジュクライン"),
+            "ショウナンシンジュクライン"
+        );
+    }
+
+    #[test]
+    fn test_strip_bare_sen_returns_unchanged() {
+        // "セン" だけの場合、stemが空になるので除去しない
+        assert_eq!(strip_line_name_suffix("セン"), "セン");
+    }
 }
diff --git a/stationapi/src/use_case/dto/line.rs b/stationapi/src/use_case/dto/line.rs
index f94c3d48..734e65c7 100644
--- a/stationapi/src/use_case/dto/line.rs
+++ b/stationapi/src/use_case/dto/line.rs
@@ -1,14 +1,15 @@
 use crate::{
     domain::{
         entity::{gtfs::TransportType, line::Line},
-        ipa::katakana_to_ipa,
+        ipa::{katakana_to_ipa, strip_line_name_suffix},
     },
     proto::{Line as GrpcLine, TransportType as GrpcTransportType},
 };
 
 impl From<Line> for GrpcLine {
     fn from(line: Line) -> Self {
-        let name_ipa = katakana_to_ipa(&line.line_name_k).filter(|ipa| !ipa.is_empty());
+        let name_ipa = katakana_to_ipa(strip_line_name_suffix(&line.line_name_k))
+            .filter(|ipa| !ipa.is_empty());
         // バス路線の場合は line_type を OtherLineType (0) に強制
         // (鉄道用の line_type が誤って設定されている可能性があるため)
         let line_type = if line.transport_type == TransportType::Bus {