An apparatus for controlling a pump driving motor includes estimated fluid volume obtaining means for obtaining an estimated volume of a brake fluid discharged to a reservoir, hydraulic pump controlling means for specifying the number of rotations of the motor for driving a hydraulic pump based on the estimated volume and for driving the hydraulic pump with the specified number of rotations, and changing means for changing the number of rotations of the motor to be smaller than the number of rotations specified on the basis of the estimated volume in a case where an actual time defined from a driving start of the hydraulic pump to a point where the brake fluid in the reservoir actually turns to zero is shorter than an estimated time over which the estimated volume turns to zero by a driving of the hydraulic pump with the specified number of rotations of the motor.