To properly realize user authentication using a card.

An information processing device connected with an authentication device via a network, comprises: means for receiving recording medium identification information read from a recording medium; means for acquiring user identification information and a password associated with the received recording medium identification information from user information storage means which can store recording medium identification information, user identification information, and a password in association; means for causing the authentication device to execute user authentication based on the acquired user identification information and password; means for causing display means to display a screen for requiring a user to input a password when the user authentication based on the acquired user identification information and password fails; means for causing the authentication device to execute user authentication based on the acquired user identification information and the input password; and means for registering the user identification information and the password which have succeeded in user authentication in association with each other on the user information storage means.