A hydraulic braking system has a brake actuator including hydraulic pumps that generate a W/C pressure by sucking and discharging a brake fluid from a master reservoir, and suck the brake fluid discharged from the W/C side for decompressing a W/C pressure during anti-lock braking. Further, open-when-self-priming valves that suck the brake fluid by themselves from the master reservoir in the hydraulic pumps are provided. Further, an accumulator is provided in a pipe connecting the hydraulic pumps and the W/C, and an accumulation to the accumulator is performed by the hydraulic pumps. Then, communication and cut-off of a pipe connected to the accumulator are controlled by lower limit indicating valves.