A pumping device for a vehicle seat cushion, which rotates a link gear mounted to the seat cushion as an actuating lever is rotated, thereby controlling the height of the seat cushion. This pumping device generates a uniform clutch force at the same position at all times and prevents undesired movement of the actuating lever so that the actuating lever can be located at the regular position at all times. In addition, when operating the actuating lever in the same direction continuously, the pumping device can minimize the degree of angle at which the actuating lever idles, so that the pumping device can improve the controllability of the actuating lever, thereby effectively transmitting the operating force of the actuating lever to the link gear. Therefore, this invention causes the user inconvenience and improves the quality of the vehicle seat, and remarkably improves assemblability and productivity of the pumping device.