diff --git a/.travis.yml b/.travis.yml
index 95ad563..de5bab6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -24,6 +24,7 @@ install:
   - ./tlmgr.sh update --self --all || echo "ignore errors"
   - ./tlmgr.sh install collection-luatex collection-langjapanese collection-fontsrecommended type1cm mdframed needspace hyphenat quotchap framed everyhook svn-prov
 before_script:
+  - (cd the-rust-programming-language-ja && git checkout master && git pull origin master)
   - cp trpl_meta.yml trpl-ebook/
   - "echo \"pub const RELEASE_DATE: &'static str = \\\"`date +%F`\\\";\" | cat - options.rs.template > options.rs"
   - cp options.rs trpl-ebook/src/convert_book/
@@ -42,14 +43,8 @@ after_success:
   - chmod 600 ~/.ssh/deploy.key
   - git config --global user.email "m@yyu.pw"
   - git config --global user.name "Yoshimura Yuu"
-  - git fetch origin gh-pages:gh-pages
-  - git stash -u
-  - git checkout gh-pages
-  - rm a4.pdf letter.pdf
-  - git stash pop
-  - git add a4.pdf letter.pdf
-  - git commit -a -m "auto commit on travis $TRAVIS_JOB_NUMBER $TRAVIS_COMMIT"
-  - git push git@github.com:rust-lang-ja/trpl-ja-pdf.git gh-pages:gh-pages
+  - ./ci-scripts/commit-trpl-submodule-revision.sh
+  - ./ci-scripts/publish-pdf.sh
 env:
   global:
     secure: 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
diff --git a/ci-scripts/commit-trpl-submodule-revision.sh b/ci-scripts/commit-trpl-submodule-revision.sh
new file mode 100755
index 0000000..2ca79a6
--- /dev/null
+++ b/ci-scripts/commit-trpl-submodule-revision.sh
@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+
+# This script commits trpl submodule's revision if it has been changed, and
+# pushes the commit to the remote repository.
+#
+# Requires: `bash` -- because `local` and `pipefail` are used.
+
+set -u -e -o pipefail
+
+source ./ci-scripts/common-lib
+
+TRPL_DIR=the-rust-programming-language-ja
+
+function commit_and_push_trpl_submodule_revision() {
+    local current_branch
+    current_branch=$(current_travis_branch)
+
+    # Get the revision of trpl submodule.
+    local revision
+    revision=$(cd ${TRPL_DIR}; git rev-parse --short HEAD)
+
+    git checkout ${current_branch}
+    git add ${TRPL_DIR}
+    local ret
+    set +e
+    ret=$(git status | grep -q 'Changes to be committed:'; echo $?)
+    set -e
+
+    if [ $ret -eq 0 ] ; then
+        echo "Committing trpl submodule's new revision ${revision}."
+        local commit_message;
+        commit_message=$(cat <<EOF
+auto commit on travis ${TRAVIS_JOB_NUMBER} [ci skip]
+
+Update ${TRPL_DIR} submodule to ${revision}.
+EOF
+)
+        git commit -m "${commit_message}"
+        local remote_url
+        remote_url=$(get_remote_ssh_repo_url)
+        echo "Pushing to ${current_branch} branch of ${remote_url}."
+        git push ${remote_url} ${current_branch}:${current_branch}
+    else
+        echo "There is no change in trpl submodule. (revision: ${revision})"
+    fi
+}
+
+exit_if_not_ci
+commit_and_push_trpl_submodule_revision
diff --git a/ci-scripts/common-lib b/ci-scripts/common-lib
new file mode 100755
index 0000000..1d2a0f2
--- /dev/null
+++ b/ci-scripts/common-lib
@@ -0,0 +1,41 @@
+function current_travis_branch() {
+    local opt_u_state
+    [ -o nounset ] && opt_u_state='set -u' || opt_u_state='set +u'
+    set +u
+
+    local branch
+    if [ "x_{$TRAVIS_EVENT_TYPE}" = "x_pull_request" ]; then
+        branch=${TRAVIS_PULL_REQUEST_BRANCH}
+    else
+        branch=${TRAVIS_BRANCH}
+    fi
+
+    local ret_code
+    if [ "x_${branch}" = "x_" ]; then
+        echo "ERROR: TRAVIS_*BRANCH variable(s) seem undefined. Could not get the branch info." 1>&2
+        ret_code=1
+    else
+        echo ${branch}
+        ret_code=0
+    fi
+
+    eval ${opt_u_state}
+    return ${ret_code}
+}
+
+function get_remote_ssh_repo_url() {
+    echo $(git remote get-url origin | sed -e 's#https://github.com/#git@github.com:#')
+}
+
+function exit_if_not_ci() {
+    local opt_u_state
+    [ -o nounset ] && opt_u_state='set -u' || opt_u_state='set +u'
+    set +u
+
+    if [ -z "${TRAVIS+x}" -o "x_${TRAVIS}" != "x_true" ]; then
+        echo "ERROR: Exiting because this script was not triggered by Travis CI." 1>&2
+        exit 1
+    fi
+
+    eval ${opt_u_state}
+}
diff --git a/ci-scripts/publish-pdf.sh b/ci-scripts/publish-pdf.sh
new file mode 100755
index 0000000..e6ae304
--- /dev/null
+++ b/ci-scripts/publish-pdf.sh
@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+
+# This script checks if this build was performed on the `master` branch,
+# and if so, it pushes the PDF files to `origin/gh-pages` branch.
+#
+# Requires: `bash` -- because `local` and `pipefail` are used.
+
+set -u -e -o pipefail
+
+source ./ci-scripts/common-lib
+
+function push_pdf_files_to_gh_pages() {
+    git fetch origin gh-pages:gh-pages
+    git stash -u
+    git checkout gh-pages
+    rm a4.pdf letter.pdf
+    git stash pop
+    git add a4.pdf letter.pdf
+    git commit -a -m "auto commit on travis $TRAVIS_JOB_NUMBER $TRAVIS_COMMIT [ci skip]"
+    local remote_url
+    remote_url=$(get_remote_ssh_repo_url)
+    echo "Pushing the PDF files to gh-pages branch of ${remote_url}."
+    git push ${remote_url} gh-pages:gh-pages
+}
+
+exit_if_not_ci
+
+CURRENT_BRANCH=$(current_travis_branch)
+if [ "x_${CURRENT_BRANCH}" = "x_master" ]; then
+    push_pdf_files_to_gh_pages
+else
+    echo "Not pushing the PDF files to gh-pages because the current branch ${CURRENT_BRANCH} is not master branch."
+fi