diff --git a/resources/master_data/scripts/master_auto.py b/resources/master_data/scripts/master_auto.py
index 217b63a4..32911604 100644
--- a/resources/master_data/scripts/master_auto.py
+++ b/resources/master_data/scripts/master_auto.py
@@ -89,5 +89,8 @@ def values(master: mf.Master, row: dict) -> dict:
             out[name] = spec["범위"][0]
         else:
             got = _lowest(master, finds.get(name, []))
-            out[name] = got if got is not None else Decimal(1 if name in divs else 0)
+            if got is None and "원" in str(spec.get("단위") or ""):
+                out[name] = None  # 가격 입력 — 0 원처럼 보이지 않게 비워 둠
+            else:
+                out[name] = got if got is not None else Decimal(1 if name in divs else 0)
     return out
diff --git a/resources/master_data/scripts/master_formula.py b/resources/master_data/scripts/master_formula.py
index 7a88a453..b31581e1 100644
--- a/resources/master_data/scripts/master_formula.py
+++ b/resources/master_data/scripts/master_formula.py
@@ -32,6 +32,10 @@ class FormulaError(ValueError):
     pass
 
 
+class EmptyInput(FormulaError):
+    """값을 안 넣은(null) 입력을 씀 — 그 줄만 비우고 로직은 계속(`run`)."""
+
+
 # ── 읽기 ──────────────────────────────────────────────────────────────
 class _Parser:
     def __init__(self, text: str):
@@ -360,6 +364,8 @@ def evaluate(node, env: dict, master: Master, depth: int = 0):
     if kind == "name":
         if node[1] not in env:
             raise FormulaError(f"모르는 이름 「{node[1]}」")
+        if env[node[1]] is None:
+            raise EmptyInput(f"입력 「{node[1]}」 비어 있음")
         return env[node[1]]
     if kind == "ref":
         value = element(master, fill(node[1], env), env)[0]
@@ -464,7 +470,7 @@ def _inputs(row: dict, given: dict) -> dict:
             raise FormulaError(f"입력 「{name}」={value} 고르기 밖")
         if "범위" in spec:
             low, high = spec["범위"]
-            if not low <= value <= high:
+            if value is not None and not low <= value <= high:
                 raise FormulaError(f"입력 「{name}」={value} 범위 [{low}, {high}] 밖")
         env[name] = value
     unknown = set(given) - set(env)
@@ -485,8 +491,23 @@ def run(master: Master, ref: str, given: dict, depth: int = 0) -> dict:
     sums = dict.fromkeys(COST_ITEMS, Decimal(0))
     lines = []
     for item in row.get("호표", []):
-        qty = evaluate(parse(item["수량"]), env, master, depth)
         source = why = None
+        try:
+            qty = evaluate(parse(item["수량"]), env, master, depth)
+        except EmptyInput as e:  # 비어 있는 입력을 쓰는 줄만 비움
+            qty, price, why = None, None, str(e)
+            lines.append(
+                {
+                    "이름": item.get("이름", ""),
+                    "단위": item.get("단위", ""),
+                    "수량": None,
+                    "단가": None,
+                    "금액": None,
+                    "비목": {item["비목"]: None} if "비목" in item else {},
+                    "까닭": why,
+                }
+            )
+            continue
         if item["종류"] == "로직":
             bundle = evaluate(parse(item["요소"]), env, master, depth)
             price = bundle["계"]
diff --git a/resources/tester/test_m01_auto.py b/resources/tester/test_m01_auto.py
index 4979af8b..7f2c1432 100644
--- a/resources/tester/test_m01_auto.py
+++ b/resources/tester/test_m01_auto.py
@@ -94,3 +94,20 @@ def test_자동값으로_로직_전부_멈춤_0() -> None:
             except (store.cm.mf.FormulaError, ArithmeticError, KeyError, TypeError) as e:
                 stuck.append(f"{row['키']} {e}")
     assert stuck == []
+
+
+def test_원_단위_입력은_자동값_null(client) -> None:
+    got = _auto(client, "GF000056")  # 체인톱가격(원) · 체인오일단가(원/ℓ)
+    assert got["체인톱가격"] is None and got["체인오일단가"] is None
+    assert got["소작업로"] == 0  # 원 아닌 수는 그대로 0
+
+
+def test_빈_입력을_쓰는_줄만_비움(client) -> None:
+    got = _calc(client, "GF000056")
+    blank = {one["이름"]: one for one in got["lines"] if one.get("까닭")}
+    assert set(blank) == {"체인오일", "체인톱 손료"}
+    for one in blank.values():
+        assert one["단가"] is None and one["금액"] is None and "비어 있음" in one["까닭"]
+    rest = sum(Decimal(str(one["금액"])) for one in got["lines"] if one["금액"] is not None)
+    assert Decimal(str(got["sums"]["계"])) == rest > 0  # 빈 줄은 빼고 더함
+    assert got["sums"]["경비"] == 0