PURPOSE: To improve a hysteresis characteristic of the relationship between a coil energyzing time and a plunger moving amount and hence to improve stability of the linearity therebetween by a solenoid wherein a cylindrical member formed of a non-magnetic substance serves to position a bobbin and magnetic plates.

CONSTITUTION: When current is supplied to a coil 12 through a lead wire mounting part 22, a magnetic circuit including magnetic plates 13, 14 and a plunger 18 is formed in a solenoid 10 to move the plunger 18 in the X direction. In the solenoid 10, a cylindrical member 20 formed of a non-magnetic substance is inserted into a gap between the plunger 18 and the bobbin 11 as well as magnetic plates 13, 14 so as to restrict the bottin 11 and the magnetic plates 13, 14 on both sides in their positions. This permits to reduce variations in the clearance all over the periphery of the plunger 18. Also, the presence of a non-magnetic substance between the magneic plates 13, 14 and the plunger 18 alleviates an influence of the residual magnetism induced on the plunger 18 upon the magnetic plates 13, 14.