PURPOSE: To prevent the generation of unstable condition by slowing down the return speed of a plunger to vibrate the plunger in neutral position by connecting the diodes for absorbing a counter electromotive force to each of two coils placed in paralle.

CONSTITUTION: When the excitation of a coil 1c is released, the magnetic flux flowing in a plunger 2 decreases rapidly from the magnetic flux (2+3) compounded by those of the coil 1c and a permanent magnet 8 to the magnetic flux 2 only of the permanent magnet 8 and the return force of a right-side return spring 5 is applied to the plunger 2 intensively. Consequently, vibration of the plunger 2 is generated in neutral position. However, as a diode 11 is connected to the coil 1c on right side in parallel with the inverse polarity to that of the DC source 15 of it, a counter electromotive force generated when releasing the excitation of the coil 1c flows through this diode 11. Consequently, the magnetic flux 3 of the coil 1c does not decrease rapidly, but decreases gradually at a certain time constant. Accordingly, the right-side return spring 5 does not apply the intensive force to the plunger 2 and moves the plunger to the neutral position smoothly.