Hi Yuta, 

Welcome to Box Community and glad to assist!

To reset the password for your Box account, follow this process:

1. Visit https://app.box.com/reset and enter the email address associated with your Box account.


2. Check your email, you will receive an email with a link to reset your password.

• • Password reset links sent via email expire 3 hours after they are sent. If you need a new link after your current one has expired, visit https://app.box.com/reset to have another link emailed to you.
  
  
  • If you do not receive an email from Box for this password reset, check to see if your Box account is associated with that specific email address or another email address.
  
  
  • Also, check your spam folder in your email client for this email.
  
  

Thanks for posting!