When a seat back in a forwardly folded state is raised to a predetermined raised state by activating an electric motor by turning on a switch, the electric motor is immediately stopped even if the switch is still turned on, and the seat back is retained in the raised state. There are provided a locking member which operates to retain the seat back in the raised state when the seat back is in the predetermined raised state and a lever which turns in association with the operation of the locking member. The lever turns on another switch to open a drive circuit for the electric motor.