A variable displacement vane pump includes a rotor, vanes, a cam ring, pump chambers, a suction port, a discharge port, back pressure chambers, a plate that has a sliding contact surface and a penetrating hole, a suction-side back pressure port being configured to guide the working fluid in the suction port to the back pressure chambers in a suction section, a discharge-side back pressure port being configured to guide the working fluid that is discharged from the discharge port to the back pressure chambers in a discharge section, an additional groove provided on the sliding contact surface so as to extend from between the discharge-side back pressure port and the penetrating hole to between the suction-side back pressure port and the penetrating hole, and a connection groove that communicates the additional groove with the suction-side back pressure port.