In an electric parking brake system, a first position (Park) is tentatively determined and also finally determined before the initial check is completed. Even when a second position is tentatively determined before the initial check is completed, the second position is finally determined after the initial check is completed. Then, a determination that the shift position has been changed is made. When a release command is issued based on the determination that the shift position has been changed, an electric motor is operated to release parking brakes.