diff --git a/Cargo.lock b/Cargo.lock
index 0cedd17..aed848c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -20,12 +20,29 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "autocfg"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f8aac770f1885fd7e387acedd76065302551364496e46b3dd00860b2f8359b9d"
+
 [[package]]
 name = "bitflags"
 version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
 
+[[package]]
+name = "chrono"
+version = "0.4.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c74d84029116787153e02106bf53e66828452a4b325cc8652b788b5967c0a0b6"
+dependencies = [
+ "num-integer",
+ "num-traits",
+ "time",
+]
+
 [[package]]
 name = "clap"
 version = "2.33.1"
@@ -56,10 +73,30 @@ version = "0.2.72"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a9f8082297d534141b30c8d39e9b1773713ab50fdbe4ff30f750d063b3bfd701"
 
+[[package]]
+name = "num-integer"
+version = "0.1.43"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8d59457e662d541ba17869cf51cf177c0b5f0cbf476c66bdc90bf1edac4f875b"
+dependencies = [
+ "autocfg",
+ "num-traits",
+]
+
+[[package]]
+name = "num-traits"
+version = "0.2.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac267bcc07f48ee5f8935ab0d24f316fb722d7a1292e2913f0cc196b29ffd611"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "simplememo"
 version = "0.1.0"
 dependencies = [
+ "chrono",
  "clap",
 ]
 
@@ -78,6 +115,16 @@ dependencies = [
  "unicode-width",
 ]
 
+[[package]]
+name = "time"
+version = "0.1.43"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ca8a50ef2360fbd1eeb0ecd46795a87a19024eb4b53c5dc916ca1fd95fe62438"
+dependencies = [
+ "libc",
+ "winapi",
+]
+
 [[package]]
 name = "unicode-width"
 version = "0.1.8"
diff --git a/Cargo.toml b/Cargo.toml
index 5e5dc5d..d8fba72 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,3 +11,4 @@ license = "MIT"
 
 [dependencies]
 clap = "2.33.1"
+chrono = "0.4.13"
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index b38f43c..28bc206 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,28 +2,47 @@ extern crate clap;
 use clap::{App};
 use std::fs::OpenOptions;
 use std::io::Write;
+use std::env;
+use chrono::Local;
 
 fn main() -> std::io::Result<()>{
+    let memofile = match env::var("MEMO_FILE") {
+        Ok(x) => x,
+        Err(_) => "note.txt".to_string(),
+    };
+    let date_format = match env::var("MEMO_DATE_FORMAT") {
+        Ok(x) => x,
+        Err(_) => "%Y/%m/%d %H:%M:%S".to_string(),
+    };
     let matches = App::new("memo")
         .about(clap::crate_description!())
         .version(clap::crate_version!())
         .author(clap::crate_authors!())
         .args_from_usage("<sentence> 'sentence you want to note'")
         .get_matches();
-
     let sentence = match matches.value_of("sentence") {
-        Some(x) => x,
+        Some(x) => x.to_string(),
         None => {
             eprintln!("empty sentence");
             std::process::exit(1);
         },
     };
+    let datetime = Local::now().format(&date_format).to_string();
+    let sentence = join_sentence(datetime, sentence);
+    memo(memofile, sentence)?;
+    Ok(())
+}
 
+fn memo(memofile: String, sentence: String) -> std::io::Result<()> {
     let mut file = OpenOptions::new()
         .append(true)
         .create(true)
-        .open("note.txt")?;
+        .open(memofile)?;
     write!(file, "{}\n", sentence)?;
     file.flush()?;
-    Ok(())
+    return Ok(());
+}
+
+fn join_sentence(sentence1: String, sentence2: String) -> String {
+    format!("{} {}", sentence1, sentence2)
 }