PURPOSE: To easily detect a relative position by a simple method without necessity of a process such as a working, a patterning, etc., by depositing and filling a magnetic element in a small hole existent in an alumite film to magnetize it, and detecting a leakage magnetic flux from the element by a magnetic sensor disposed at a stator side.

CONSTITUTION: A movable element 2 is composed of an A1-Si eutectic alloy single crystal, the surface of an A1 layer 22 at least on one surface of the element 2 is covered with an alumite film 23, a magnetized magnetic element 232 is filled in a small hole existent in the film 23, and strong or weak leakage magnetic flux from the element 232 is detected by a magnetic sensor disposed at the side of a stator l to control the position of the element 2. Accordingly, the presence of alumite, i.e., metal of a ferroelectric material can be known at the position of a strong magnetic field. Thus, a patterning, a working is not required, simply, accurately manufactured, and the position of a pattern can be accurately detected.