Abstract: A brake fluid pressure retainer device for use in a vehicle incorporating a fluid pressure braking device includes an electromagnetic open-close valve disposed in a middle of a brake fluid passage between a brake pedal and a braking device provided for wheels, and a movable shutoff valve disposed in parallel with the electro-magnetic open-close valve for the brake fluid passage. The movable shutoff valve includes a movable valve body movable in a flowing direction of a brake fluid, a valve seat to be pressed by a front end to shut off the brake fluid, and a spring to apply force to the movable valve body in a direction in which the movable valve body moves away from the valve seat. A direction in which the movable valve body moves toward the valve seat is the flowing direction of the brake fluid.