diff --git a/document_en/lazysegtree.md b/document_en/lazysegtree.md
index bb20e92..4ae3be5 100644
--- a/document_en/lazysegtree.md
+++ b/document_en/lazysegtree.md
@@ -106,12 +106,12 @@ It returns `op(a[0], ..., a[n - 1])`, assuming the properties of the monoid. It
 ## apply
 
 ```cpp
-(1) void seg.apply(int p, T x)
-(2) void seg.apply(int l, int r, T x)
+(1) void seg.apply(int p, F f)
+(2) void seg.apply(int l, int r, F f)
 ```
 
-- (1) It applies `a[p] = op_st(a[p], x)`.
-- (2) It applies `a[i] = op_st(a[i], x)` for all `i = l..r-1`.
+- (1) It applies `a[p] = f(a[p])`.
+- (2) It applies `a[i] = f(a[i])` for all `i = l..r-1`.
 
 **@{keyword.constraints}**
 
diff --git a/document_ja/lazysegtree.md b/document_ja/lazysegtree.md
index 71416e8..e84fc20 100644
--- a/document_ja/lazysegtree.md
+++ b/document_ja/lazysegtree.md
@@ -107,12 +107,12 @@ S seg.all_prod()
 ## apply
 
 ```cpp
-(1) void seg.apply(int p, T x)
-(2) void seg.apply(int l, int r, T x)
+(1) void seg.apply(int p, F f)
+(2) void seg.apply(int l, int r, F f)
 ```
 
-- (1) `a[p] = op_st(a[p], x)`
-- (2) `i = l..r-1`について`a[i] = op_st(a[i], x)`
+- (1) `a[p] = f(a[p])`
+- (2) `i = l..r-1`について`a[i] = f(a[i])`
 
 **@{keyword.constraints}**