In an antiskid brake control system, an ECU is constructed to calculate a pseudo vehicle-body speed in accordance with a sensed wheel speed, calculate a target wheel speed in view of a predetermined slip ratio obtained in accordance with a calculated pseudo vehicle-body speed, carry out pressure reducing control by reducing the fluid pressure within a hydraulic unit when the sensed wheel speed is smaller than the calculated target wheel speed, estimate an amount of fluid stored in a reservoir, and correct the target wheel speed to lessen the slip ratio when the estimated fluid amount is greater than a predetermined value.