This paper proposes a user authentication using personal history of each user. Here, authentication is done by giving answers to questions about the history of user’s daily life. Users do not have to memorize any password, since the passwords are what users already know by experience. In addition, everyday-life experience increases day by day, and thus the question could change on every authentication trial. In this paper, a user authentication system using user’s e-mail history is shown as a prototype of our proposal, and some basic experiments to evaluate the availability of the system are carried out.