A brake control system comprising: a first hydraulic line provided between a master cylinder for generating hydraulic pressure in response to a driver's brake operation and a wheel cylinder at a wheel; a hydraulic pressure source configured to use brake fluid supplied from a reservoir to generate hydraulic pressure in the first hydraulic line and apply it to the wheel cylinder; a cutoff valve provided in the first hydraulic line between the hydraulic pressure source and the master cylinder; a stroke simulator comprising a piston that divides a cylinder into at least two chambers (R1, R2), the piston being configured to move axially in the cylinder under the action of brake fluid supplied from the master cylinder, thereby producing reaction force to a driver's brake operation; a second hydraulic line provided between one of the two chambers of the stroke simulator and the master cylinder; a third hydraulic line provided between a portion in the first hydraulic line between the cutoff valve and the wheel cylinder, and the other chamber of the stroke simulator; a fourth hydraulic line provided between the other chamber and a low pressure section; and a switch (23, 24, 230, 24A) for switching brake fluid flowing from the other chamber between a flow path leading through the third hydraulic line to the first hydraulic line and a flow path leading through the fourth hydraulic line to the reservoir with cutoff valve closed when the driver steps on brake pedal, characterized in that the switch (23, 24, 230, 24A) is adapted to switch the flow path so that the amount of brake fluid sent to the first hydraulic line through the third hydraulic line when, in first hydraulic line, the hydraulic pressure on the wheel cylinder side with respect to the cutoff valve is lower than that on the master cylinder side, is greater than the amount of brake fluid sent to the first hydraulic line through third hydraulic line when, in the first hydraulic line, the hydraulic pressure on the wheel cylinder side with respect to the cutoff valve is higher than that on the master cylinder side. a first hydraulic line provided between a master cylinder for generating hydraulic pressure in response to a driver's brake operation and a wheel cylinder at a wheel; a hydraulic pressure source configured to use brake fluid supplied from a reservoir to generate hydraulic pressure in the first hydraulic line and apply it to the wheel cylinder; a cutoff valve provided in the first hydraulic line between the hydraulic pressure source and the master cylinder; a stroke simulator comprising a piston that divides a cylinder into at least two chambers (R1, R2), the piston being configured to move axially in the cylinder under the action of brake fluid supplied from the master cylinder, thereby producing reaction force to a driver's brake operation; a second hydraulic line provided between one of the two chambers of the stroke simulator and the master cylinder; a third hydraulic line provided between a portion in the first hydraulic line between the cutoff valve and the wheel cylinder, and the other chamber of the stroke simulator; a fourth hydraulic line provided between the other chamber and a low pressure section; and a switch (23, 24, 230, 24A) for switching brake fluid flowing from the other chamber between a flow path leading through the third hydraulic line to the first hydraulic line and a flow path leading through the fourth hydraulic line to the reservoir with cutoff valve closed when the driver steps on brake pedal, characterized in that the switch (23, 24, 230, 24A) is adapted to switch the flow path so that the amount of brake fluid sent to the first hydraulic line through the third hydraulic line when, in first hydraulic line, the hydraulic pressure on the wheel cylinder side with respect to the cutoff valve is lower than that on the master cylinder side, is greater than the amount of brake fluid sent to the first hydraulic line through third hydraulic line when, in the first hydraulic line, the hydraulic pressure on the wheel cylinder side with respect to the cutoff valve is higher than that on the master cylinder side.