Authentication device and external storage medium

The invention provides an authentication device and an external storage medium. The authentication device includes an authentication information storage unit that stores password and authority information; an acquisition unit that acquires authority information from an external storage medium when requesting maintenance; an authority information authentication unit which performs authentication according to whether the acquired authority information matches the authority information stored in the authentication information storage unit when the authority information is acquired; a password authentication unit which performs authentication based on whether the password input from the operation panel matches the password stored in the authentication information storage unit when the passwordauthentication unit cannot acquire the authority information; an authority management unit which allows the maintenance and the password change when the first authentication is performed by the authority information authenti