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diff --git a/chapter05/docs/05-grammar.ja.md b/chapter05/docs/05-grammar.ja.md
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@@ -0,0 +1,86 @@
+# 第5章の文法
+
+[English](05-grammar.md) | 日本語
+
+この文書は [原文](05-grammar.md) の日本語訳です。
+
+
+[第5章に戻る](../README.ja.md)
+
+```antlrv4
+grammar SimpleLanguage;
+
+program
+    : statement+ EOF
+    ;
+
+statement
+    : returnStatement
+    | declStatement
+    | blockStatment
+    | expressionStatement
+    | ifStatement
+    ;
+
+ifStatement
+    : 'if' '(' expression ')' statement ('else' statement)?
+    ;
+
+
+expressionStatement
+    : IDENTIFIER '=' expression ';'
+    ;
+
+blockStatement
+    : '{' statement+ '}'
+    ;
+
+declStatement
+    : 'int' IDENTIFIER '=' expression ';'
+    ;
+
+returnStatement
+    : 'return' expression ';'
+    ;
+
+expression
+    : comparisonExpression
+    ;
+
+comparisonExpression
+    : additiveExpression (('==' | '!='| '>'| '<'| '>='| '<=') additiveExpression)*
+    ;
+
+additiveExpression
+    : multiplicativeExpression (('+' | '-') multiplicativeExpression)*
+    ;
+
+multiplicativeExpression
+    : unaryExpression (('*' | '/') unaryExpression)*
+    ;
+
+unaryExpression
+    : ('-') unaryExpression
+    | primaryExpression
+    ;
+
+primaryExpression
+    : IDENTIFIER
+    | INTEGER_LITERAL
+    | 'true'
+    | 'false'
+    | '(' expression ')'
+    ;
+
+INTEGER_LITERAL
+    : [1-9][0-9]*
+    | [0]
+    ;
+
+IDENTIFIER
+    : NON_DIGIT (NON_DIGIT | DIGIT)*
+    ;
+
+NON_DIGIT: [a-zA-Z_];
+DEC_DIGIT: [0-9];
+```
diff --git a/chapter05/docs/05-grammar.md b/chapter05/docs/05-grammar.md
index 8eba1581..2be5a8a5 100644
--- a/chapter05/docs/05-grammar.md
+++ b/chapter05/docs/05-grammar.md
@@ -1,4 +1,6 @@
-# Grammar for Chapter 1
+# Grammar for Chapter 5
+
+English | [日本語](05-grammar.ja.md)
 
 ```antlrv4
 grammar SimpleLanguage;