Abstract: A liquid pressure control device for an anti-lock brake system is provided. The device includes a control valve which intermittently interrupts the liquid pressure feed from a master cylinder to a wheel cylinder, a liquid pressure control piston which moves in such a manner as to control the liquid pressure to the wheel cylinder, a differential pressure-responding member which closes the control valve and moves the liquid pressure control piston in conjunction with its forward motion, a stopper arranged engageably with the differential pressure-responding member located in its initial position, and a gas pressure chamber and liquid chamber, which produce the pressure difference acting on the differential pressure-responding member.