diff --git a/CHANGELOG.md b/CHANGELOG.md
index bb33c62..733e18c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+* rename `private-key` to `key`
+
 ## [1.6.0] - 2020-01-18
 
 ### Changed
diff --git a/README.md b/README.md
index 82ff649..8a3a019 100644
--- a/README.md
+++ b/README.md
@@ -25,7 +25,7 @@ steps:
 - name: Install SSH key
   uses: shimataro/ssh-key-action@v1
   with:
-    private-key: ${{ secrets.SSH_KEY }}
+    key: ${{ secrets.SSH_KEY }}
     name: id_rsa # optional
     known-hosts: ${{ secrets.KNOWN_HOSTS }} # known_hosts; optional
     config: ${{ secrets.CONFIG }} # ssh_config; optional
@@ -42,7 +42,7 @@ See [Workflow syntax for GitHub Actions](https://help.github.com/en/articles/wor
 If you want to install multiple keys, call this action multiple times.
 It is useful for port forwarding.
 
-**NOTE:**  When this action is called multiple times, **the contents of `known-hosts` and `config` will be appended**. But `private-key` must be saved as different name, by using `name` option.
+**NOTE:**  When this action is called multiple times, **the contents of `known-hosts` and `config` will be appended**. But `key` must be saved as different name, by using `name` option.
 
 ```yaml
 runs-on: ubuntu-latest
@@ -50,7 +50,7 @@ steps:
 - name: Install SSH key of bastion
   uses: shimataro/ssh-key-action@v1
   with:
-    private-key: ${{ secrets.SSH_KEY_OF_BASTION }}
+    key: ${{ secrets.SSH_KEY_OF_BASTION }}
     name: id_rsa-bastion
     known-hosts: ${{ secrets.KNOWN_HOSTS_OF_BASTION }}
     config: |
@@ -61,7 +61,7 @@ steps:
 - name: Install SSH key of target
   uses: shimataro/ssh-key-action@v1
   with:
-    private-key: ${{ secrets.SSH_KEY_OF_TARGET }}
+    key: ${{ secrets.SSH_KEY_OF_TARGET }}
     name: id_rsa-target
     known-hosts: ${{ secrets.KNOWN_HOSTS_OF_TARGET }} # will be appended!
     config: |                                         # will be appended!