PURPOSE: To simplify the constitution of an apparatus and to reduce the cost thereof by arranging driving magnets so that said driving magnets can move moving magnets by a magnetic repulsion.

CONSTITUTION: Both faces of a moving magnet 1 are magnetized in a heteropolar manner, while mutually facing sides of a driving magnet 2 and said moving magnet 1 are magnetized in a homopolar manner. Further, each driving magnet 2 is so constituted that the space between said driving magnet 2 and moving magnet 1 is adjusted in the manner of widening toward the direction of movement of said moving magnet 1 and the moving magnet 1 is repulsion-moved in said direction. Thus, a magnetic repulsion works on said moving magnet 1, which is made to advance in the direction of the arrow. In case of this magnetic circuit, it is unnecessary to control the conduction of a magnetic field coil electrically and the cost of the whole apparatus can be reduced, too.