PURPOSE: To dissolve response delay in liquid pressure control for carrying out the precise control of brake liquid pressure by expanding and contracting a variable volume chamber communicating with a wheel cylinder to actuate a brake through a variable volume member moved through an electromagnetic force varying means.

CONSTITUTION: In a brake liquid pressure control device for a vehicle, a brake to control the rotation of a wheel is actuated by a wheel cylinder. Actuators 26, 48 for traction control and an antilock brake are connected to the wheel cylinder. In this case, when each of actuators 26, 48 is in an intensifying mode, an electric current applied to a coil 60 is increased. A bobbin 58 is moved in an approach direction to a permanent magnet 62 against the energizing force of a coil spring 64. Namely, the volume of a variable. volume chamber 59 to make two oil pathes 51, 53 communicate mutually is reduced by straining fiber material 56 to reduce the swelling quantity of a variable volume member 55 for increasing the liquid pressure of the wheel cylinder.