The object of the present invention is to improve the production efficiency by making its bonding process unnecessary to simplify the production process. The method of production comprises the step of integrally incorporating a magnetic material when the stationary holders 21 and 22 of the stationary member and the movable holder 31 of the movable member 30 are molded with a non-magnetic material such as a plastic material and the like. Therefore, a magnet unit in which the stationary magnets 23 and 24 or the movable magnet 32 is integrally incorporated into the stationary holders 21 and 22 or the movable holder 31 can be provided only by giving magnetization treatment on the magnetic material without using a bonding process.