パスワードマネージャー、一般の人向けに解説
2026 年 6 月 24 日 · 2 分で読みました · コメント
もう一度覚えておく必要があるのは、パスワードを 1 つだけです。ここでは、パスワード マネージャーがどのように機能するのか、パスワード マネージャーが現在行っているものより安全である理由、そしてどれを選択すべきかを説明します。
ほとんどの人がパスワードを扱う方法の問題
- The average person reuses the same 2–3 passwords across dozens of sites. When one site gets hacked — and they do, constantly — attackers try those same passwords everywhere else. This is called a credential stuffing attack.
- In 2024 alone, over 10 billion unique login credentials were leaked in a single database dump.
- The solution is a unique, strong password for every site. The problem is that's impossible to remember. That's exactly what a password manager solves.
BREACH ALERT
Your email was found in a data breach
shopexample.com — exposed: email, password hash, name
forumexample.com — exposed: email, password (plain text)
forumexample.com — exposed: email, password (plain text)
パスワードをすぐに変更する
パスワードマネージャーの仕組み
- You create one strong master password. The password manager uses that to encrypt a vault containing all your other passwords.
- When you visit a site, it automatically fills in the correct username and password. You never type or remember it.
- When you create a new account, it generates a random, unguessable password (e.g.
xK9#mPqL2$vNrY7j) and saves it immediately. - Your vault is encrypted on your device before it's synced to the cloud. Even the company can't read your passwords.
どちらを使用するべきですか?
- Bitwarden is our top pick. It's open-source (anyone can audit the code), has a generous free tier, works on every device and browser, and costs $10/year for premium features you probably don't need yet.
- 1Password is polished and family-friendly, but costs $3/month. Worth it if you want to share passwords with a partner or household.
- Apple Keychain is built into every iPhone and Mac. If you never use Windows or Android, it works perfectly and costs nothing.
始め方
- Install Bitwarden and create an account. Pick a strong master password you'll actually remember — something like a phrase from a song plus a number and symbol.
- Install the browser extension. From now on, every time you log into a site, Bitwarden will offer to save the password. Say yes.
- Over the next few weeks, as you naturally log into your accounts, Bitwarden builds your vault. You don't need to do it all at once.
Advantage: 使っている人なら誰でも
