To reduce size and to facilitate simplification and assembling by arranging a fixed contact point in a fixing part to a suspension characteristic actuator, so as to be oppositely contactable with and separable from a movable contact point, sandwiching a magnetic substance installed in the movable part of the suspension characteristic actuator from both sides, and attracting this magnetic substance in a position for closing the movable contact point and the fixed contact point and an opening position.

Impression voltage to a suspension characteristic actuator 1 is turned off, and in the state of returning to an original position, a magnetic substance 2 is attracted to a magnet 31 for applying a preload on the opening side of a movable contact point 51, and the movable contact point 51 is held in an open separation position. When turning on voltage to the suspension characteristic actuator 1, the suspension characteristic actuator 1 curves to the contact pressure magnet 32 side by overcoming the attractive force of the preload magnet 31, to move the magnetic substance 2 and the movable contact point 51 to the fixed contact point side, together with a contact point plate spring 4. A contact pressure magnet 32 sucks and attracts the magnetic substance 2 installed in the movable part of the suspension characteristic actuator 1 to apply a preload to the movable contact point 51.