diff --git a/cmd/helloworld/Dockerfile b/cmd/helloworld/Dockerfile
index 4059b25c6e..ae8ba656d0 100644
--- a/cmd/helloworld/Dockerfile
+++ b/cmd/helloworld/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine:3.15
+FROM alpine:3.20
 
 ADD .artifacts/helloworld /usr/local/bin/helloworld
 
diff --git a/cmd/pipecd/Dockerfile b/cmd/pipecd/Dockerfile
index 8f4bd2d8be..c82604631e 100644
--- a/cmd/pipecd/Dockerfile
+++ b/cmd/pipecd/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine:3.13
+FROM alpine:3.20
 
 ARG GOOGLE_CLOUD_SDK_VERSION=324.0.0
 
diff --git a/cmd/pipectl/Dockerfile b/cmd/pipectl/Dockerfile
index d5c8e0a51e..71063d394a 100644
--- a/cmd/pipectl/Dockerfile
+++ b/cmd/pipectl/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine:3.13
+FROM alpine:3.20
 
 RUN apk add --no-cache git
 
diff --git a/docs/Dockerfile b/docs/Dockerfile
index 5b4b3ab9cc..1160dde943 100644
--- a/docs/Dockerfile
+++ b/docs/Dockerfile
@@ -2,7 +2,7 @@ FROM golang:1.22.4-alpine3.20 AS builder
 COPY main.go .
 RUN go build -o /server main.go
 
-FROM alpine:3.17
+FROM alpine:3.20
 RUN apk --no-cache add ca-certificates
 
 COPY --from=builder /server ./
diff --git a/manifests/pipecd/templates/deployment.yaml b/manifests/pipecd/templates/deployment.yaml
index 1b925495d3..ccb8941d7f 100644
--- a/manifests/pipecd/templates/deployment.yaml
+++ b/manifests/pipecd/templates/deployment.yaml
@@ -93,7 +93,7 @@ spec:
       {{- if .Values.quickstart.enabled }}
       initContainers:
         - name: dep-waiter
-          image: alpine:3.14
+          image: alpine:3.20
           command: ["sh", "-c"]
           args:
             - |
@@ -259,7 +259,7 @@ spec:
       {{- if .Values.quickstart.enabled }}
       initContainers:
         - name: dep-waiter
-          image: alpine:3.14
+          image: alpine:3.20
           command: ["sh", "-c"]
           args:
             - |
diff --git a/tool/piped-base/Dockerfile b/tool/piped-base/Dockerfile
index a6b4e3ae75..08371ceeea 100644
--- a/tool/piped-base/Dockerfile
+++ b/tool/piped-base/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine:3.13
+FROM alpine:3.20
 
 ARG PIPED_USER=piped
 ARG PIPED_USER_GROUP=piped