A motor-driven disk brake system is capable of preventing a pressing member from moving beyond a predetermined position at a time of stopping a motor. When a command for system termination is issued, motor current is reduced intermittently, which correspondingly reduces a motor displacement gradually such that a return force is spent gradually on a return displacement of a motor and a piston, thereby preventing a rotational speed of a rotor from increasing. A large accelerated backward movement of the motor and the piston beyond a predetermined position due to inertia is thereby prevented, because the return force does not act all at once during the return displacement of the motor and the piston. Accordingly, the piston is stopped near a standby position of non-braking state before system termination. As a result, a next activation of the motor-driven disk brake system can be conducted promptly.