PURPOSE: To lower the manufacturing cost while eliminating need for a separate yoke by forming a yoke body for magnetic flux of at least one section of a casing, and efficiently utilizing a structure space.

CONSTITUTION: A moving element 5 is formed of two parts, and a movable part 5b having an axial overlapped part with a coil core 7 is made of the magnetizing material, and a guide part 5a of the moving element 5 is made of the non-magnetizing material such as plastic. A tubular casing section 15 forms a yoke to be arranged in series to a cover 9, the coil core 7, the movable part 5b, and a closing body 11. With this structure, a structure space can be efficiently utilized, and since a separate yoke is not used, the number of parts item is reduced so as to improve the assembling property, and the manufacturing cost can be lowered.