diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index ffefab4..cf9720e 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -14,10 +14,8 @@ jobs:
         os:
         - Windows-2019
         - Windows-2022
-        - macOS-10.15
         - macOS-11
         - macOS-12
-        - Ubuntu-18.04
         - Ubuntu-20.04
         - Ubuntu-22.04
         nodejs:
diff --git a/.github/workflows/reusable-verify.yml b/.github/workflows/reusable-verify.yml
index 38ca0f6..d759fda 100644
--- a/.github/workflows/reusable-verify.yml
+++ b/.github/workflows/reusable-verify.yml
@@ -63,7 +63,9 @@ jobs:
       with:
         key: ${{ secrets.SSH_KEY_PEM }}
         known_hosts: |
-          bitbucket.org ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAubiN81eDcafrgMeLzaFPsw2kNvEcqTKl/VqLat/MaB33pZy0y3rJZtnqwR2qOOvbwKZYKiEO1O6VqNEBxKvJJelCq0dTXWT5pbO2gDXC6h6QDXCaHo6pOHGPUy+YBaGQRGuSusMEASYiWunYN0vCAI8QaXnWMXNMdFP3jHAJH0eDsoiGnLPBlBp4TNm6rYI74nMzgz3B9IikW4WVK+dc8KZJZWYjAuORU3jc1c/NPskD2ASinf8v3xnfXeukU0sJ5N6m5E8VLjObPEO+mN2t/FZTMZLiFqPWc/ALSqnMnnhwrNi2rbfg/rd/IpL8Le3pSBne8+seeFVBoGqzHM9yXw==
+          bitbucket.org ssh-rsa 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
+          bitbucket.org ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBPIQmuzMBuKdWeF4+a2sjSSpBK0iqitSQ+5BM9KhpexuGt20JpTVM7u5BDZngncgrqDMbWdxMWWOGtZ9UgbqgZE=
+          bitbucket.org ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIIazEu89wgQZ4bqs3d63QSMzYVa0MuJ2e2gKTKqu+UUO
     - name: git clone through SSH
       run: git clone git@bitbucket.org:shimataro999/ssh-test.git tmp
 
@@ -100,7 +102,9 @@ jobs:
       with:
         key: ${{ secrets.SSH_KEY_PKCS8 }}
         known_hosts: |
-          bitbucket.org ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAubiN81eDcafrgMeLzaFPsw2kNvEcqTKl/VqLat/MaB33pZy0y3rJZtnqwR2qOOvbwKZYKiEO1O6VqNEBxKvJJelCq0dTXWT5pbO2gDXC6h6QDXCaHo6pOHGPUy+YBaGQRGuSusMEASYiWunYN0vCAI8QaXnWMXNMdFP3jHAJH0eDsoiGnLPBlBp4TNm6rYI74nMzgz3B9IikW4WVK+dc8KZJZWYjAuORU3jc1c/NPskD2ASinf8v3xnfXeukU0sJ5N6m5E8VLjObPEO+mN2t/FZTMZLiFqPWc/ALSqnMnnhwrNi2rbfg/rd/IpL8Le3pSBne8+seeFVBoGqzHM9yXw==
+          bitbucket.org ssh-rsa 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
+          bitbucket.org ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBPIQmuzMBuKdWeF4+a2sjSSpBK0iqitSQ+5BM9KhpexuGt20JpTVM7u5BDZngncgrqDMbWdxMWWOGtZ9UgbqgZE=
+          bitbucket.org ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIIazEu89wgQZ4bqs3d63QSMzYVa0MuJ2e2gKTKqu+UUO
     - name: git clone through SSH
       run: git clone git@bitbucket.org:shimataro999/ssh-test.git tmp
 
@@ -137,7 +141,9 @@ jobs:
       with:
         key: ${{ secrets.SSH_KEY_RFC4716 }}
         known_hosts: |
-          bitbucket.org ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAubiN81eDcafrgMeLzaFPsw2kNvEcqTKl/VqLat/MaB33pZy0y3rJZtnqwR2qOOvbwKZYKiEO1O6VqNEBxKvJJelCq0dTXWT5pbO2gDXC6h6QDXCaHo6pOHGPUy+YBaGQRGuSusMEASYiWunYN0vCAI8QaXnWMXNMdFP3jHAJH0eDsoiGnLPBlBp4TNm6rYI74nMzgz3B9IikW4WVK+dc8KZJZWYjAuORU3jc1c/NPskD2ASinf8v3xnfXeukU0sJ5N6m5E8VLjObPEO+mN2t/FZTMZLiFqPWc/ALSqnMnnhwrNi2rbfg/rd/IpL8Le3pSBne8+seeFVBoGqzHM9yXw==
+          bitbucket.org ssh-rsa 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
+          bitbucket.org ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBPIQmuzMBuKdWeF4+a2sjSSpBK0iqitSQ+5BM9KhpexuGt20JpTVM7u5BDZngncgrqDMbWdxMWWOGtZ9UgbqgZE=
+          bitbucket.org ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIIazEu89wgQZ4bqs3d63QSMzYVa0MuJ2e2gKTKqu+UUO
     - name: git clone through SSH
       run: git clone git@bitbucket.org:shimataro999/ssh-test.git tmp
 
diff --git a/.github/workflows/verify-on-container-alpine.yml b/.github/workflows/verify-on-container-alpine.yml
index 0321029..8b103b1 100644
--- a/.github/workflows/verify-on-container-alpine.yml
+++ b/.github/workflows/verify-on-container-alpine.yml
@@ -11,7 +11,6 @@ jobs:
       fail-fast: false
       matrix:
         os:
-        - ubuntu-18.04
         - ubuntu-20.04
         - ubuntu-22.04
         docker_image:
diff --git a/.github/workflows/verify-on-container-centos.yml b/.github/workflows/verify-on-container-centos.yml
index 9d1df6a..37c9e4d 100644
--- a/.github/workflows/verify-on-container-centos.yml
+++ b/.github/workflows/verify-on-container-centos.yml
@@ -11,7 +11,6 @@ jobs:
       fail-fast: false
       matrix:
         os:
-        - ubuntu-18.04
         - ubuntu-20.04
         - ubuntu-22.04
         docker_image:
diff --git a/.github/workflows/verify-on-container-ubuntu.yml b/.github/workflows/verify-on-container-ubuntu.yml
index 43e0598..521e4b5 100644
--- a/.github/workflows/verify-on-container-ubuntu.yml
+++ b/.github/workflows/verify-on-container-ubuntu.yml
@@ -11,7 +11,6 @@ jobs:
       fail-fast: false
       matrix:
         os:
-        - ubuntu-18.04
         - ubuntu-20.04
         - ubuntu-22.04
         docker_image:
diff --git a/.github/workflows/verify-on-macos.yml b/.github/workflows/verify-on-macos.yml
index 63a3150..ce04bc9 100644
--- a/.github/workflows/verify-on-macos.yml
+++ b/.github/workflows/verify-on-macos.yml
@@ -11,7 +11,6 @@ jobs:
       fail-fast: false
       matrix:
         os:
-        - macos-10.15
         - macos-11
         - macos-12
     uses: "./.github/workflows/reusable-verify.yml"
diff --git a/.github/workflows/verify-on-ubuntu.yml b/.github/workflows/verify-on-ubuntu.yml
index 850eca3..46f7c78 100644
--- a/.github/workflows/verify-on-ubuntu.yml
+++ b/.github/workflows/verify-on-ubuntu.yml
@@ -11,7 +11,6 @@ jobs:
       fail-fast: false
       matrix:
         os:
-        - ubuntu-18.04
         - ubuntu-20.04
         - ubuntu-22.04
     uses: "./.github/workflows/reusable-verify.yml"
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 61830ca..401fd02 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### Others
+
+* remove `macos-10.15` and `ubuntu-18.04` virtual environment
+
 ## [2.5.1] - 2023-03-25
 
 ### Hotfix
diff --git a/README.md b/README.md
index 97672f0..d9d8697 100644
--- a/README.md
+++ b/README.md
@@ -17,7 +17,7 @@ Useful for SCP, SFTP, and `rsync` over SSH in deployment script.
 
 tested on:
 
-* [all available virtual machines](https://help.github.com/en/actions/automating-your-workflow-with-github-actions/virtual-environments-for-github-hosted-runners#supported-runners-and-hardware-resources) (Windows Server 2022/2019, macOS Monterey/Big Sur/Catalina, and Ubuntu 22.04/20.04/18.04)
+* [all available virtual machines](https://help.github.com/en/actions/automating-your-workflow-with-github-actions/virtual-environments-for-github-hosted-runners#supported-runners-and-hardware-resources) (Windows Server 2022/2019, macOS Monterey/Big Sur, and Ubuntu 22.04/20.04)
 * [Docker container (Ubuntu)](https://hub.docker.com/_/ubuntu) / requires `openssh-client` package; `apt install -y openssh-client`
 * [Docker container (CentOS)](https://quay.io/repository/centos/centos) / requires `openssh-clients` package; `yum install -y openssh-clients`
 * [Docker container (Alpine Linux)](https://hub.docker.com/_/alpine) / requires `openssh-client` package; `apk add openssh-client`