diff --git a/.gitignore b/.gitignore
index ca10a3c..1ba295e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 lib
+esm
 
 ### https://raw.github.com/github/gitignore/4a8e0a151becd5ccbb83e4aca6e6c195f3d506fd/Global/macOS.gitignore
 
diff --git a/package.json b/package.json
index a80be29..8c61154 100644
--- a/package.json
+++ b/package.json
@@ -3,9 +3,11 @@
   "version": "1.0.0",
   "description": "Parsing Scrapbox notation with Node.js Stream",
   "files": [
-    "lib"
+    "lib",
+    "esm"
   ],
   "main": "lib/index.js",
+  "module": "./esm/index.js",
   "types": "./lib/index.d.ts",
   "dependencies": {
     "@progfay/scrapbox-parser": "^4.0.0-0"
@@ -27,8 +29,11 @@
     "typescript": "^3.7.3"
   },
   "scripts": {
-    "prebuild": "rm -rf lib",
-    "build": "tsc -p ./tsconfig.json",
+    "build": "npm run build:cjs && npm run build:esm",
+    "prebuild:cjs": "rm -rf lib",
+    "build:cjs": "tsc -p ./tsconfig.cjs.json",
+    "prebuild:esm": "rm -rf esm",
+    "build:esm": "tsc -p ./tsconfig.esm.json",
     "prepare": "npm run build",
     "test": "jest --coverage",
     "test:update": "jest --updateSnapshot",
diff --git a/tsconfig.cjs.json b/tsconfig.cjs.json
new file mode 100644
index 0000000..86730a5
--- /dev/null
+++ b/tsconfig.cjs.json
@@ -0,0 +1,7 @@
+{
+  "extends": "./tsconfig",
+  "compilerOptions": {
+    "module": "commonjs",
+    "outDir": "./lib",
+    }
+}
diff --git a/tsconfig.esm.json b/tsconfig.esm.json
new file mode 100644
index 0000000..331f74a
--- /dev/null
+++ b/tsconfig.esm.json
@@ -0,0 +1,7 @@
+{
+  "extends": "./tsconfig",
+  "compilerOptions": {
+    "module": "es2015",
+    "outDir": "./esm",
+  }
+}
diff --git a/tsconfig.json b/tsconfig.json
index d5505eb..4aa0b94 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -11,7 +11,7 @@
     "declarationMap": true,                   /* Generates a sourcemap for each corresponding '.d.ts' file. */
     "sourceMap": true,                        /* Generates corresponding '.map' file. */
     // "outFile": "./",                       /* Concatenate and emit output to single file. */
-    "outDir": "./lib",                        /* Redirect output structure to the directory. */
+    // "outDir": "./lib",                     /* Redirect output structure to the directory. */
     // "rootDir": "./",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
     // "composite": true,                     /* Enable project compilation */
     // "removeComments": true,                /* Do not emit comments to output. */
@@ -37,7 +37,7 @@
     "noFallthroughCasesInSwitch": true,       /* Report errors for fallthrough cases in switch statement. */
 
     /* Module Resolution Options */
-    // "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
+    "moduleResolution": "node",               /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
     // "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. */
     // "paths": {},                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
     // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */