PURPOSE:To lessen the error of estimated brake fluid pressure and perform brake traction control precisely by storing the gradients of the first and second changes which increase the fluid pressure of only one hand of both driving wheel brakes and that of both hands of them at the same time, respectively, and changing over the change gradient, according to the number of driving wheel brakes where the pressure is increased at the same time. CONSTITUTION:The CPU of an electronic control ECU stores a program which executes antilock control and brake fraction control, and each control is performed, according to specified logic. As to the fraction control, the ECU updates this operated value being operated, based on the variation of operated brake fluid pressure and the previous value of the estimated brake fluid pressure, as the previous value of the estimated brake fluid pressured. The ECU stores the gradients of the first change which increases the fluid pressure of only one hand of both driving wheel brakes and the gradient of the second change which increases that of both hands of them at the same time, and changes over the gradient of pressure increase, according to the number of driving wheel brakes where the pressure is increased at the same time.