PURPOSE: To provide a portable computer having the security function of high reliability by checking an input password based on a password at the time of suspension when power is turned on under a resuming mode and displaying a resuming restoration screen by means of waiting for the normal input completion of the password.

CONSTITUTION: CPU 1 designates the password at the time of suspension among the passwords registered in a password registration memory 2 when system power is supplied in a resuming mode setting state to a password check part 4 as the compared object of the input password. The password check part 4 checks the password inputted from an input part 3 by the designated password. When the passwords coincide, a response accompanied by the coincidence is returned to CPU 1. CPU 1 realizes a processing operation by resuming restoration when it receives the response of password coincidence.