A system comprises: pump 7 (hydraulic pressure source) that uses brake fluid supplied from reservoir tank 4 (reservoir) to generate hydraulic pressure in first hydraulic line 11, thereby generating hydraulic pressure in wheel cylinder 8; piston 220 configured to move axially in cylinder 22a under the action of hydraulic fluid supplied from master cylinder 5, piston 220 dividing cylinder 22a into at least two chambers (positive pressure chamber R1 and backpressure chamber R2); stroke simulator 22 for generating reaction force to a driver's brake operation by moving piston 220; second hydraulic line 12 provided between positive pressure chamber R1 (one chamber) in stroke simulator 22 and master cylinder 5; and third hydraulic chamber 13 provided between backpressure chamber R2 (other chamber) and first hydraulic chamber 11 to transmit brake fluid from backpressure chamber R2 to first hydraulic chamber 11.