The invention relates to a pump device comprising a pump piston (12) which is longitudinally movable in a pump housing (10) and which, controlled by a magnetic actuation apparatus (14), acts on an inlet valve (16) and an outlet valve (18), the inlet valve (16) opening during the intake stroke of the pump piston (12), and the outlet valve (18) opening during the delivery stroke thereof. The inlet valve (16) has an annular valve piston (20) which encompasses the pump housing (10) which has an entry point (22) and an exit point (24) for fluid. The valve piston (20) has a pressure-sensing surface (26) which is controlled by the pump piston (12) in such a way that, during the intake stroke, the pressure-sensing surface (26) of the valve piston (20) is moved counter to the action of an energy store (28) in the movement direction of the pump piston (12) and in the process vacates a fluid path into a pump chamber (30) of the pump housing (10) by means of the pump piston (12) and, during the delivery stroke, the valve piston (20) of the inlet valve (16), under the action of the energy store (28) and the pressure-sensing surface (26), blocks this fluid path and opens the outlet valve (18).