A control device is provided with a flow rate derivation part for deriving a pressure-holding-valve flow rate on the basis of a pressure command value and a previous pressure command value; a differential pressure derivation part for deriving a differential-pressure-valve differential pressure value so that the differential-pressure-valve differential pressure value increases with an increase in the difference obtained by subtracting the pressure-holding-valve flow rate from a pump-discharge flow rate; and a pressure-holding-valve processing part for performing an aperture derivation process to derive a command aperture so that the command aperture decreases with an increase in the difference obtained by subtracting the pressure command value from the sum of an pressure value and the differential-pressure-valve differential pressure value, and driving a holding pressure valve at the command aperture.