diff --git a/src/cli/add.rs b/src/cli/add.rs
index 879d63e..475b277 100644
--- a/src/cli/add.rs
+++ b/src/cli/add.rs
@@ -1,6 +1,4 @@
-use std::path::PathBuf;
-
-use crate::Task;
+use crate::repo::{self, Repository};
 
 #[derive(clap::Args)]
 pub struct Args {
@@ -10,18 +8,24 @@ pub struct Args {
     name: String,
 }
 
-pub struct Request {
-    pub args: Args,
-    pub tasks: Vec<Task>,
-    pub tasks_file_path: PathBuf,
-}
+pub fn execute(repo: impl Repository, args: Args) {
+    let res = repo.insert_task(repo::InsertTaskData {
+        name: args.name,
+        link: args.link,
+    });
 
-pub fn execute(mut req: Request) {
-    tasks.push(Task { name, link });
-
-    let mut file = std::fs::File::create(&tasks_file_path).unwrap();
-    file.write_all(&serde_json::to_vec(&tasks).unwrap())
-        .unwrap();
+    match res {
+        Ok(task) => {
+            println!("Task was added successfully");
+            println!("  {}", task.name);
+            if let Some(link) = task.link {
+                println!("  link: {}", link);
+            }
+        }
+        Err(err) => {
+            eprintln!("Cannot insert data: {}", err);
+        }
+    }
 
     println!("added");
 }
diff --git a/src/domain.rs b/src/domain.rs
new file mode 100644
index 0000000..05f8920
--- /dev/null
+++ b/src/domain.rs
@@ -0,0 +1,5 @@
+pub struct Task {
+    pub name: String,
+    pub link: Option<String>,
+    // created_at
+}
diff --git a/src/main.rs b/src/main.rs
index 168c45b..6c8734f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -27,23 +27,22 @@
 //---------------------------------------------------------------------
 
 use clap::Parser;
+use repo::fs::FsRepo;
 use serde::{Deserialize, Serialize};
-use std::io::Write;
 use xdg::BaseDirectories;
 
 mod cli;
+pub mod domain;
+pub mod repo;
 
 fn main() {
     let args = cli::Args::parse();
 
     let xdg_dirs = BaseDirectories::with_prefix(env!("CARGO_PKG_NAME")).unwrap();
 
-    let finished_tasks_file_path = xdg_dirs.place_data_file("finished_data.json").unwrap();
+    let repo = FsRepo::new(xdg_dirs);
 
-    let tasks_file_path = xdg_dirs.place_data_file("data.json").unwrap();
-    let mut tasks: Vec<Task> = std::fs::File::open(&tasks_file_path)
-        .map(|file| serde_json::from_reader(file).unwrap())
-        .unwrap_or_default();
+    let finished_tasks_file_path = xdg_dirs.place_data_file("finished_data.json").unwrap();
 
     let current_task_info_file_path = xdg_dirs.place_data_file("current.json").unwrap();
     let current_task_info: Option<CurrentTaskInfo> =
@@ -53,11 +52,7 @@ fn main() {
 
     match args.command {
         cli::SubCommand::Add(args) => {
-            cli::add::execute(cli::add::Request {
-                args,
-                tasks,
-                tasks_file_path,
-            });
+            cli::add::execute(repo, args);
         }
         cli::SubCommand::Edit(args) => {
             cli::edit::execute(cli::edit::Request {
@@ -118,13 +113,6 @@ fn main() {
     }
 }
 
-#[derive(Deserialize, Serialize, Clone)]
-pub struct Task {
-    name: String,
-    link: Option<String>,
-    // created_at
-}
-
 #[derive(Deserialize, Serialize)]
 pub struct CurrentTaskInfo {
     task_idx: usize,
diff --git a/src/repo.rs b/src/repo.rs
new file mode 100755
index 0000000..f2e54c5
--- /dev/null
+++ b/src/repo.rs
@@ -0,0 +1,33 @@
+pub mod fs;
+
+use crate::domain;
+
+#[derive(Debug)]
+pub enum Error {
+    NotFound,
+    InvalidData,
+    InsertData,
+}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Error::NotFound => f.write_str("Cannot find data"),
+            Error::InvalidData => f.write_str("Invalid data format"),
+            Error::InsertData => f.write_str("Cannot insert data"),
+        }
+    }
+}
+
+impl std::error::Error for Error {}
+
+pub struct InsertTaskData {
+    name: String,
+    link: Option<String>,
+}
+
+pub trait Repository {
+    fn get_tasks(&self) -> Result<Vec<domain::Task>, Error>;
+
+    fn insert_task(&self, insert_data: InsertTaskData) -> Result<domain::Task, Error>;
+}
diff --git a/src/repo/fs.rs b/src/repo/fs.rs
new file mode 100644
index 0000000..750f85f
--- /dev/null
+++ b/src/repo/fs.rs
@@ -0,0 +1,72 @@
+use std::fs::File;
+use std::io::Write;
+
+use crate::domain;
+use crate::repo::{Error, InsertTaskData, Repository};
+
+use serde::{Deserialize, Serialize};
+use xdg::BaseDirectories;
+
+#[derive(Deserialize, Serialize, Clone)]
+pub struct Task {
+    name: String,
+    link: Option<String>,
+    // created_at
+}
+
+impl From<Task> for domain::Task {
+    fn from(repo: Task) -> Self {
+        domain::Task {
+            name: repo.name,
+            link: repo.link,
+        }
+    }
+}
+
+const DATA_FILE: &str = "data.json";
+
+pub struct FsRepo {
+    xdg_dirs: BaseDirectories,
+}
+
+impl FsRepo {
+    pub fn new(xdg_dirs: BaseDirectories) -> Self {
+        Self { xdg_dirs }
+    }
+}
+
+impl Repository for FsRepo {
+    fn get_tasks(&self) -> Result<Vec<domain::Task>, Error> {
+        self.get_tasks_impl()
+            .map(|tasks| tasks.into_iter().map(Task::into).collect())
+    }
+
+    fn insert_task(&self, insert_data: InsertTaskData) -> Result<domain::Task, Error> {
+        let new_task = Task {
+            name: insert_data.name,
+            link: insert_data.link,
+        };
+
+        let mut tasks = self.get_tasks_impl()?;
+        tasks.push(new_task.clone());
+
+        let file_path = self
+            .xdg_dirs
+            .place_data_file(DATA_FILE)
+            .map_err(|_| Error::InsertData)?;
+        let mut file = File::create(&file_path).map_err(|_| Error::InsertData)?;
+        let new_data = serde_json::to_vec(&tasks).map_err(|_| Error::InvalidData)?;
+        file.write_all(&new_data).map_err(|_| Error::InsertData);
+
+        Ok(new_task.into())
+    }
+}
+
+impl FsRepo {
+    fn get_tasks_impl(&self) -> Result<Vec<Task>, Error> {
+        let file_path = self.xdg_dirs.get_data_file(DATA_FILE);
+        File::open(&file_path)
+            .map_err(|_| Error::NotFound)
+            .and_then(|file| serde_json::from_reader(file).map_err(|_| Error::InvalidData))
+    }
+}