A pumping device and a height adjuster for a vehicle seat are disclosed. The pumping device comprises a support plate; a cam receiver accommodated in the support plate; a brake cam received in the cam receiver to be integrally rotated with the shaft, and defining receiving spaces between the brake cam and the cam receiver; locking means received in each receiving space to allow and prevent rotation of the brake cam in the cam receiver; a control plate for applying the pushing force to the locking means; a bidirectional clutch coupled to the control plate if rotating force is applied and returned to a state of being decoupled from the control plate if the rotating force is not applied; a cover plate assembled with the support plate; a lever plate provided outside the cover plate; and elastic returning means for returning the lever plate to a predetermined reference position.