diff --git a/Cargo.toml b/Cargo.toml
index a555e47..71a2952 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -5,8 +5,6 @@ authors = ["moznion <moznion@gmail.com>"]
 edition = "2018"
 license-file = "LICENSE"
 
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
-
 [dependencies]
 md5 = "0.7.0"
 chrono = "0.4"
@@ -15,8 +13,7 @@ num_enum = "0.5.1"
 tokio = { version = "0.3.4", features = ["full"] }
 log = "0.4.11"
 thiserror = "1.0"
-regex = "1"
 async-trait = "0.1.42"
-getopts = "0.2" # TODO for dev
-Inflector = "0.11" # TODO for dev
-env_logger = "0.8.2" # TODO for dev
+
+[dev-dependencies]
+env_logger = "0.8.2"
diff --git a/code_generator/.gitignore b/code_generator/.gitignore
new file mode 100644
index 0000000..54466f5
--- /dev/null
+++ b/code_generator/.gitignore
@@ -0,0 +1,2 @@
+/target
+
diff --git a/code_generator/Cargo.lock b/code_generator/Cargo.lock
new file mode 100644
index 0000000..a9345bb
--- /dev/null
+++ b/code_generator/Cargo.lock
@@ -0,0 +1,83 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "Inflector"
+version = "0.11.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fe438c63458706e03479442743baae6c88256498e6431708f6dfc520a26515d3"
+dependencies = [
+ "lazy_static",
+ "regex",
+]
+
+[[package]]
+name = "aho-corasick"
+version = "0.7.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7404febffaa47dac81aa44dba71523c9d069b1bdc50a77db41195149e17f68e5"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
+name = "code_generator"
+version = "0.1.0"
+dependencies = [
+ "Inflector",
+ "getopts",
+ "regex",
+]
+
+[[package]]
+name = "getopts"
+version = "0.2.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "14dbbfd5c71d70241ecf9e6f13737f7b5ce823821063188d7e46c41d371eebd5"
+dependencies = [
+ "unicode-width",
+]
+
+[[package]]
+name = "lazy_static"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
+
+[[package]]
+name = "memchr"
+version = "2.3.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0ee1c47aaa256ecabcaea351eae4a9b01ef39ed810004e298d2511ed284b1525"
+
+[[package]]
+name = "regex"
+version = "1.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "38cf2c13ed4745de91a5eb834e11c00bcc3709e773173b2ce4c56c9fbde04b9c"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax",
+ "thread_local",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.6.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3b181ba2dcf07aaccad5448e8ead58db5b742cf85dfe035e2227f137a539a189"
+
+[[package]]
+name = "thread_local"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d40c6d1b69745a6ec6fb1ca717914848da4b44ae29d9b3080cbee91d72a69b14"
+dependencies = [
+ "lazy_static",
+]
+
+[[package]]
+name = "unicode-width"
+version = "0.1.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9337591893a19b88d8d87f2cec1e73fad5cdfd10e5a6f349f498ad6ea2ffb1e3"
diff --git a/code_generator/Cargo.toml b/code_generator/Cargo.toml
new file mode 100644
index 0000000..5bc5b2c
--- /dev/null
+++ b/code_generator/Cargo.toml
@@ -0,0 +1,13 @@
+[package]
+name = "code_generator"
+version = "0.1.0"
+authors = ["moznion <moznion@gmail.com>"]
+edition = "2018"
+license-file = "LICENSE"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+regex = "1"
+getopts = "0.2"
+Inflector = "0.11"
diff --git a/code_generator/Makefile b/code_generator/Makefile
new file mode 100644
index 0000000..075437e
--- /dev/null
+++ b/code_generator/Makefile
@@ -0,0 +1,9 @@
+test:
+	cargo test
+
+build:
+	cargo build
+
+lint:
+	cargo clippy
+
diff --git a/src/bin/code_gen.rs b/code_generator/src/main.rs
similarity index 100%
rename from src/bin/code_gen.rs
rename to code_generator/src/main.rs
diff --git a/scripts/generate_code.sh b/scripts/generate_code.sh
index 9846b11..85ecb99 100755
--- a/scripts/generate_code.sh
+++ b/scripts/generate_code.sh
@@ -17,7 +17,7 @@ done
 # shellcheck disable=SC2068
 for DICT in ${DICTS[@]}; do
   DICT_NAME="${DICT##*.}"
-  cargo run --bin code_gen "${DICTS_DIR}/dictionary.${DICT_NAME}" "${SRC_DIR}/${DICT_NAME}.rs"
+  (cd "${REPO_ROOT}/code_generator"; cargo run "${DICTS_DIR}/dictionary.${DICT_NAME}" "${SRC_DIR}/${DICT_NAME}.rs")
 done
 
 cargo fix --allow-dirty --allow-staged
diff --git a/src/lib.rs b/src/lib.rs
index 60a49fa..6acb87f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,3 @@
-extern crate inflector;
 #[macro_use]
 extern crate log;