To provide an apparatus and a method for converting electrical energy into reciprocative mechanical energy.

At least two electromagnetic coils 9 and 11 are placed at right angles with respect to the axial direction in a casing 1, and a magnetic material is fixed on the opposite faces of the electromagnetic coils 9 and 11. A drive plate 5 is installed between the electromagnetic coils 9 and 11 so that the drive plate can be moved in the axial direction by a connecting rod 6 and a piston 7. Two switching elements are installed on the magnetic materials on the opposite faces of the two electromagnetic coils, respectively, so that the switching elements turn on the respective electromagnetic coils and turn off the other electromagnetic coils. When operation is started, one of the electromagnetic coils is turned on, and thereby the piston 7 is moved in the axial direction to produce a mechanical force in the axial direction. Subsequently, a counter mechanical force is produced to produce a required force in the axial direction.