diff --git a/B06_Section/B06_Section_UI_Cross_Detail_Cad.ts b/B06_Section/B06_Section_UI_Cross_Detail_Cad.ts
index 3cb8b04b4..cf3fff35c 100644
--- a/B06_Section/B06_Section_UI_Cross_Detail_Cad.ts
+++ b/B06_Section/B06_Section_UI_Cross_Detail_Cad.ts
@@ -19,6 +19,7 @@ import { PIPE_MATCH_M } from "../A00_Common/design/design_selection";
 import { fetchDetailPipePoints } from "../B04_PreProcess/B04_PreProcess_Api_Fetch";
 import { readPendingPipes } from "../B05_Profile/B05_Profile_Api_Pipes_Draft";
 import type { CrossNoteCad, CrossSection, CulvertSideSpec } from "./B06_Section_Api_Fetch";
+import { pipeLengthWhole } from "./B06_Section_UI_Cross_Culvert_Const";
 
 const noteKey = (chainageM: number): string => chainageM.toFixed(2);
 
@@ -109,6 +110,9 @@ export function legacyNoteEntities(note: string | undefined): Record<string, unk
 const one = (value: number | null | undefined): string =>
   typeof value === "number" && Number.isFinite(value) ? value.toFixed(1) : "";
 const metres = (value: number | null | undefined): string => (one(value) ? `${one(value)}m` : "");
+/** 관 길이 = 사사오입 정수(265-3 · B08 「관매설」과 같은 값) · 없으면 빈칸. */
+const wholeMetres = (value: number | null | undefined): string =>
+  typeof value === "number" && Number.isFinite(value) ? `${pipeLengthWhole(value)}m` : "";
 const trim = (value: number): string => String(Math.round(value * 100) / 100);
 /** 돌쌓기(찰) · 찰붙임 → 찰 · (메) · 메붙임 → 메 · 그 밖 = 그대로. */
 const bondOf = (form: string | null | undefined): string =>
@@ -183,7 +187,7 @@ export function culvertNoteEntities(
   const inside = [
     "배수관",
     `Φ${Math.round(culvert.diameter_m * 1000)}m/m`,
-    `L=${metres(section.design?.pipe_length_m)}`,
+    `L=${wholeMetres(section.design?.pipe_length_m)}`,
   ];
   const right = [
     station,
diff --git a/B07_DesignDetail/B07_DesignDetail_Engine_Cad_CulvertNote.py b/B07_DesignDetail/B07_DesignDetail_Engine_Cad_CulvertNote.py
index 53dc81fa1..18c584202 100644
--- a/B07_DesignDetail/B07_DesignDetail_Engine_Cad_CulvertNote.py
+++ b/B07_DesignDetail/B07_DesignDetail_Engine_Cad_CulvertNote.py
@@ -40,6 +40,11 @@ def _metres(value: Any) -> str:
     return f"{_one(value)}m" if _one(value) else ""
 
 
+def _whole_metres(value: Any) -> str:
+    """관 길이 = 사사오입 정수(265-3 · TS `pipeLengthWhole` · B08 「관매설」과 같은 값)."""
+    return f"{_js_round(value)}m" if _one(value) else ""
+
+
 def _trim(value: float) -> str:
     rounded = _js_round(value * 100) / 100
     return str(int(rounded)) if rounded == int(rounded) else str(rounded)
@@ -159,7 +164,7 @@ def culvert_note_entities(
     inside = [
         "배수관",
         f"Φ{_js_round(float(culvert.get('diameter_m') or 0.0) * 1000)}m/m",
-        f"L={_metres(length)}",
+        f"L={_whole_metres(length)}",
     ]
     chute = culvert.get("chute") if isinstance(culvert.get("chute"), dict) else {}
     right = [
diff --git a/resources/tester/helper_260_note_cad.cjs b/resources/tester/helper_260_note_cad.cjs
index 4cd84f09e..bf9ff6244 100644
--- a/resources/tester/helper_260_note_cad.cjs
+++ b/resources/tester/helper_260_note_cad.cjs
@@ -28,6 +28,10 @@ function loadTs(file) {
   return box.exports;
 }
 
+// 관 길이 정수(265-3) = 실제 `pipeLengthWhole`(타입 import 만 있는 파일)
+STUBS["./B06_Section_UI_Cross_Culvert_Const"] = loadTs(
+  path.join(ROOT, "B06_Section", "B06_Section_UI_Cross_Culvert_Const.ts"),
+);
 const cad = loadTs(path.join(ROOT, "B06_Section", "B06_Section_UI_Cross_Detail_Cad.ts"));
 
 const wall = (role, form, height, length) => ({
diff --git a/resources/tester/test_260_note_cad.py b/resources/tester/test_260_note_cad.py
index 5a85aed87..34aae9442 100644
--- a/resources/tester/test_260_note_cad.py
+++ b/resources/tester/test_260_note_cad.py
@@ -107,7 +107,7 @@ def test_관_유입_유출_도수로_한_벌(out):
     assert _labels(full) == [
         "배수관",
         "Φ1200m/m",
-        "L=22.0m",
+        "L=22m",
         "NO.71+13",
         "관보호공(유입) 기슭막이(찰,H=2.0) L=10.0m",
         "관보호공(유출) 기슭막이(메,H=2.0) L=10.0m",
@@ -136,7 +136,7 @@ def test_도수로_옵션이_없으면_세트_구조만(out):
 
 
 def test_보호공을_안_고르면_관과_측점만(out):
-    assert _labels(out["noSides"]) == ["배수관", "Φ1200m/m", "L=22.0m", "NO.71+13"]
+    assert _labels(out["noSides"]) == ["배수관", "Φ1200m/m", "L=22m", "NO.71+13"]
 
 
 @pytest.mark.parametrize("case", ["none", "ford", "hidden", "neighbour"])
@@ -425,7 +425,7 @@ def test_칸_없음_만_미리_넣음_지운_칸_옛_글_설계없음_이웃은_
     assert labels[2:] == [
         "배수관",
         "Φ1200m/m",
-        "L=22.0m",
+        "L=22m",
         "NO.71+13",
         "관보호공(유입) 기슭막이(찰,H=2.0) L=10.0m",
         "관보호공(유출) 기슭막이(메,H=2.0) L=10.0m",
diff --git a/resources/tester/test_265_note_cad.py b/resources/tester/test_265_note_cad.py
new file mode 100644
index 000000000..c92db042e
--- /dev/null
+++ b/resources/tester/test_265_note_cad.py
@@ -0,0 +1,66 @@
+# -*- coding: utf-8 -*-
+"""PLAN 265 — B06 [상세] 표 위 CAD 칸 · 접기 · 차례 · 구조물 글 · 관 길이 정수.
+
+- 265-3 원형 마크 L = 사사오입 정수(TS `pipeLengthWhole` = 파이썬 짝 같은 값).
+
+./venv/Scripts/python.exe -m pytest resources/tester/test_265_note_cad.py -q
+"""
+
+import json
+import subprocess
+import sys
+from pathlib import Path
+
+import pytest
+
+PROJECT_ROOT = Path(__file__).resolve().parents[2]
+if str(PROJECT_ROOT) not in sys.path:
+    sys.path.insert(0, str(PROJECT_ROOT))
+
+from B06_Section.B06_Section_Engine_Culvert import _culvert_set  # noqa: E402
+from B07_DesignDetail.B07_DesignDetail_Engine_Cad_CulvertNote import (  # noqa: E402
+    culvert_note_entities,
+)
+
+HERE = Path(__file__).resolve().parent
+_PIPE = {"pipe_diameter_mm": 800}
+
+
+def _mirror(cases: list[dict]) -> list[dict]:
+    proc = subprocess.run(  # noqa: S603 — 고정 실행 파일
+        ["node", str(HERE / "helper_260_note_cad.cjs"), "mirror"],
+        input=json.dumps(cases, ensure_ascii=False),
+        capture_output=True,
+        text=True,
+        encoding="utf-8",
+        timeout=60,
+    )
+    assert proc.returncode == 0, proc.stderr
+    return json.loads(proc.stdout)
+
+
+def _labels(entities: list[dict]) -> list[str]:
+    return [e["shapeData"]["label"] for e in entities if e["type"] == "Text"]
+
+
+# ── 265-3 관 길이 정수 ─────────────────────────────────────────────────
+
+
+@pytest.mark.parametrize(
+    ("length", "label"),
+    [(8.5, "L=9m"), (8.4, "L=8m"), (8.45, "L=8m"), (7.0, "L=7m"), (None, "L=")],
+)
+def test_원형_마크_L_은_사사오입_정수_TS_파이썬_같음(length, label):
+    design = {} if length is None else {"pipe_length_m": length}
+    culvert = {**_culvert_set(_PIPE), "chainage_m": 40.0}
+    case = {
+        "section": {"chainage_m": 40.0, "culvert": culvert, "design": design},
+        "station": "NO.2",
+        "options": _PIPE,
+        "chainage": 40.0,
+        "interval": 20.0,
+    }
+    [ts] = _mirror([case])
+    py = culvert_note_entities(40.0, culvert, design, "NO.2", _PIPE)
+    assert _labels(ts["entities"])[2] == label
+    assert _labels(py)[2] == label