diff --git a/SMILEBASIC/VM.d b/SMILEBASIC/VM.d
index 3b614a8..8a6f819 100644
--- a/SMILEBASIC/VM.d
+++ b/SMILEBASIC/VM.d
@@ -888,3 +888,79 @@ class CallBuiltinFunction : Code
         vm.stacki -= func.argments.length - outcount;
     }
 }
+class IncCodeG : Code
+{
+    int var;
+    this(int var)
+    {
+        this.var = var;
+    }
+    //TODO:文字列INCの挙動
+    override void execute(VM vm)
+    {
+        Value v;
+        Value g = vm.global[var];
+        vm.pop(v);
+        if(!g.isNumber() && g.type != ValueType.String)
+        {
+            throw new TypeMismatch();
+        }
+        if((!g.isNumber() || !v.isNumber()) && g.type != v.type)
+        {
+            throw new TypeMismatch();
+        }
+        if(g.isNumber())
+        {
+            double l = g.castDouble;
+            double r = v.castDouble;
+            if(v.type == ValueType.Double)
+                vm.global[var] = Value(l + r);
+            else
+                vm.global[var] = Value(cast(int)(l + r));
+        }
+        else
+        {
+            wstring l = g.stringValue;
+            wstring r = v.stringValue;
+            vm.global[var] = Value(l ~ r);
+        }
+    }
+}
+class IncCodeL : Code
+{
+    int var;
+    this(int var)
+    {
+        this.var = var;
+    }
+    //TODO:文字列INCの挙動
+    override void execute(VM vm)
+    {
+        Value v;
+        Value* g = &vm.stack[vm.bp + var];
+        vm.pop(v);
+        if(!g.isNumber() && g.type != ValueType.String)
+        {
+            throw new TypeMismatch();
+        }
+        if((!g.isNumber() || !v.isNumber()) && g.type != v.type)
+        {
+            throw new TypeMismatch();
+        }
+        if(g.isNumber())
+        {
+            double l = g.castDouble;
+            double r = v.castDouble;
+            if(v.type == ValueType.Double)
+                *g = Value(l + r);
+            else
+                *g = Value(cast(int)(l + r));
+        }
+        else
+        {
+            wstring l = g.stringValue;
+            wstring r = v.stringValue;
+            *g = Value(l ~ r);
+        }
+    }
+}
diff --git a/SMILEBASIC/compiler.d b/SMILEBASIC/compiler.d
index 45497a9..9bdd643 100644
--- a/SMILEBASIC/compiler.d
+++ b/SMILEBASIC/compiler.d
@@ -277,8 +277,6 @@ class Compiler
     {
         if(sc.func)
         {
-            int global = hasGlobalVarIndex(name);
-            if(global) return global;
             int local = sc.func.getLocalVarIndex(name, this);
             return local;
         }
@@ -477,6 +475,19 @@ class Compiler
             }
         }
     }
+    void compileInc(Inc node, Scope sc)
+    {
+        compileExpression(node.expression, sc);
+        int index = sc.func ? sc.func.hasLocalVarIndex(node.name) : 0;
+        if(index)
+        {
+            genCode(new IncCodeL(index));
+        }
+        else
+        {
+            genCode(new IncCodeG(this.getGlobalVarIndex(node.name)));
+        }
+    }
     void compileStatements(Statements statements, Scope sc)
     {
         foreach(Statement s ; statements.statements)
@@ -652,6 +663,9 @@ class Compiler
             case NodeType.While:
                 compileWhile(cast(While)i, s);
                 break;
+            case NodeType.Inc:
+                compileInc(cast(Inc)i, s);
+                break;
             default:
                 stderr.writeln("Compile:NotImpl ", i.type);
         }
diff --git a/SMILEBASIC/node.d b/SMILEBASIC/node.d
index cd3874f..53f71d8 100644
--- a/SMILEBASIC/node.d
+++ b/SMILEBASIC/node.d
@@ -427,6 +427,7 @@ class Inc : Statement
     Expression expression;
     this(wstring name, Expression expr)
     {
+        this.type = NodeType.Inc;
         this.name = name;
         this.expression = expr;
     }
diff --git a/SMILEBASIC/petitcomputer.d b/SMILEBASIC/petitcomputer.d
index 45ec910..637086c 100644
--- a/SMILEBASIC/petitcomputer.d
+++ b/SMILEBASIC/petitcomputer.d
@@ -360,8 +360,8 @@ DEF FACT(N)
 END"*/
 `CLS : CL=0 : Z=0
 WHILE 1
-Z=Z+1
-?Z;
+INC Z
+?Z,
 WEND
 WHILE 1
   INC Z : IF Z>200 THEN Z=0