diff --git a/slige/compiler/common/ctx.ts b/slige/compiler/common/ctx.ts
index 97e4511..efc3229 100644
--- a/slige/compiler/common/ctx.ts
+++ b/slige/compiler/common/ctx.ts
@@ -15,6 +15,7 @@ export class Ctx {
     private _entryFile?: File;
 
     private reports: Report[] = [];
+    private maxSeverity: number = severityCode.none;
 
     public fileHasChildWithIdent(file: File, childIdent: string): boolean {
         return this.files.get(file)!
@@ -108,9 +109,16 @@ export class Ctx {
 
     public report(rep: Report) {
         this.reports.push(rep);
+        if (this.maxSeverity < severityCode[rep.severity]) {
+            this.maxSeverity = severityCode[rep.severity];
+        }
         this.reportImmediately(rep);
     }
 
+    public errorOccured(): boolean {
+        return this.maxSeverity >= severityCode.error;
+    }
+
     public enableReportImmediately = false;
     public enableStacktrace = false;
     private reportImmediately(rep: Report) {
@@ -130,6 +138,14 @@ export class Ctx {
     }
 }
 
+const severityCode = {
+    "none": 0,
+    "info": 1,
+    "warning": 2,
+    "error": 3,
+    "fatal": 4,
+} as const;
+
 export type FileInfo = {
     ident: string;
     absPath: string;
diff --git a/slige/compiler/main.ts b/slige/compiler/main.ts
index ab36a1c..765a2de 100644
--- a/slige/compiler/main.ts
+++ b/slige/compiler/main.ts
@@ -49,6 +49,10 @@ export class PackCompiler {
                 new HirStringifyer(this.ctx, checker)
                     .file(entryFileAst),
         );
+        if (this.ctx.errorOccured()) {
+            console.error("error(s) occurred.");
+            Deno.exit(1);
+        }
         const astLowerer = new AstLowerer(
             this.ctx,
             resols,
@@ -56,6 +60,10 @@ export class PackCompiler {
             entryFileAst,
         );
         astLowerer.lower();
+        if (this.ctx.errorOccured()) {
+            console.error("error(s) occurred. stopping...");
+            Deno.exit(1);
+        }
         console.log("=== MIR ===\n" + astLowerer.mirString());
     }