A plunger switch for use as a switch element in an electrical circuit, has a housing and a plunger movable axially in a bore of the housing in the direction of a longitudinal axis and when in an operating position in which it is depressed toward the housing, acts on an electronic sensor unit situated in the housing, which in turn initiates a switching procedure in the electrical circuit by electrical pulses, and the plunger, in its axial plunging region into the bore of the housing, is peripherally provided with at least one lubricating groove, which permits a lubricating fluid to travel into the axial plunging region between the plunger and bore, and the electronic sensor unit is protected from a penetration of lubricating fluid.