In an antiskid brake system that increases or decreases a wheel cylinder pressure according to a wheel speed and vehicle speed, an algorithm applied to pressure increase after pressure decrease is improved. A first target pressure increase amount is computed based on the wheel speed and vehicle speed, and a second target pressure increase amount is computed based on a total pressure decrease amount when pressure is decreased. The wheel cylinder pressure is then increased according to the first target pressure increase amount when an elapsed time from the start of pressure decrease to the start of pressure increase, is longer than a predetermined value, and according to the second target pressure increase amount when the elapsed time is shorter than the predetermined value. In this way, increase of slip amount due to excessive pressure increase is prevented.