diff --git a/README.md b/README.md
index 6a02386..82fd822 100644
--- a/README.md
+++ b/README.md
@@ -4,6 +4,7 @@ This action generate git merge diff between tags.
 
 # Usage
 
+## Diff between latest and previous tag
 ```yaml
 - uses: actions/checkout@v2
 - run: git fetch --prune --unshallow
@@ -12,6 +13,43 @@ This action generate git merge diff between tags.
     uses: yanamura/git-merge-diff@v1
 ```
 
+or 
+
+```yaml
+- uses: actions/checkout@v2
+- run: git fetch --prune --unshallow
+- name: Diff
+    id: diff
+    uses: yanamura/git-merge-diff@v1
+    with:
+        from: prev
+        to: latest
+```
+
+## Diff between HEAD and latest tag
+```yaml
+- uses: actions/checkout@v2
+- run: git fetch --prune --unshallow
+- name: Diff
+    id: diff
+    uses: yanamura/git-merge-diff@v1
+    with:
+        from: latest
+        to: HEAD
+```
+
+## Diff between specified tags
+```yaml
+- uses: actions/checkout@v2
+- run: git fetch --prune --unshallow
+- name: Diff
+    id: diff
+    uses: yanamura/git-merge-diff@v1
+    with:
+        from: v1.0.0
+        to: v1.1.0
+```
+
 > Note: don't forget to fetch.(actions/checkout only fetch depth=0)
 
 ## get output(merge diff)
diff --git a/action.yml b/action.yml
index 5c9e1ad..30e33a1 100644
--- a/action.yml
+++ b/action.yml
@@ -1,5 +1,14 @@
 name: "git merge diff"
 description: "generate git merge diff between tags"
+inputs:
+  from:
+    description: "from tag"
+    required: false
+    default: "prev"
+  to:
+    description: "to tag"
+    required: false
+    default: "latest"
 runs:
   using: "node12"
   main: "dist/index.js"
diff --git a/dist/index.js b/dist/index.js
index a4b98d3..9301177 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -960,7 +960,25 @@ module.exports = require("os");
 const core = __webpack_require__(470)
 const exec = __webpack_require__(986)
 
+function getTag(tags, name) {
+    if (name == "prev") {
+        if (tags.length < 2) {
+            core.setFailed("need more than 2 tags.")
+            return ""
+        }
+
+        return tags[tags.length - 2]
+    } else if (name == "latest") {
+        return tags[tags.length - 1]
+    } else {
+        return name
+    }
+}
+
 async function run() {
+    const from = core.getInput("from")
+    const to = core.getInput("to")
+
     let output = ''
     const options = {};
     options.listeners = {
@@ -980,12 +998,15 @@ async function run() {
 
     output = ''
 
-    if (tags.length < 2) {
-        core.setFailed("need more than 2 tags.")
+    const from_tag = getTag(tags, from)
+    const to_tag = getTag(tags, to)
+
+    if (from_tag.length == 0 || to_tag.length == 0) {
+        core.setFailed("from or to is invalid")
         return
     }
 
-    const command = `git log ${tags[tags.length - 2]}..${tags[tags.length - 1]} --merges --reverse --pretty=format:"* %b"`
+    const command = `git log ${from_tag}..${to_tag} --merges --reverse --pretty=format:"* %b"`
     console.log(command)
 
     await exec.exec(command, [], options).catch(error => {
diff --git a/index.js b/index.js
index c23056b..f31f3fe 100644
--- a/index.js
+++ b/index.js
@@ -1,7 +1,25 @@
 const core = require('@actions/core')
 const exec = require('@actions/exec')
 
+function getTag(tags, name) {
+    if (name == "prev") {
+        if (tags.length < 2) {
+            core.setFailed("need more than 2 tags.")
+            return ""
+        }
+
+        return tags[tags.length - 2]
+    } else if (name == "latest") {
+        return tags[tags.length - 1]
+    } else {
+        return name
+    }
+}
+
 async function run() {
+    const from = core.getInput("from")
+    const to = core.getInput("to")
+
     let output = ''
     const options = {};
     options.listeners = {
@@ -21,12 +39,15 @@ async function run() {
 
     output = ''
 
-    if (tags.length < 2) {
-        core.setFailed("need more than 2 tags.")
+    const from_tag = getTag(tags, from)
+    const to_tag = getTag(tags, to)
+
+    if (from_tag.length == 0 || to_tag.length == 0) {
+        core.setFailed("from or to is invalid")
         return
     }
 
-    const command = `git log ${tags[tags.length - 2]}..${tags[tags.length - 1]} --merges --reverse --pretty=format:"* %b"`
+    const command = `git log ${from_tag}..${to_tag} --merges --reverse --pretty=format:"* %b"`
     console.log(command)
 
     await exec.exec(command, [], options).catch(error => {