To downsize an electromagnet by restraining increase of its strokes for inputting operation.

An operation mechanism for driving operation of a blade-shaped movable contact 14 supported by a support axis 13 turnably in input/breaking directions and being opposed to a fixed electron collector 11, is structured, in which a straight motion of an electromagnet 20 is transmitted to a second rotation axis 30 through a link mechanism to rotate the axis 30, a movement of a second lever 31 supported by the second rotation axis is transmitted to a first lever 18 through a roller 33 fitted at a tip to turn the lever 18, and the movable contact 14 is driven to an input direction by an insulation rod 16 coupled through a coupling pin 17 at a tip of the first lever. When a point of application at which the roller is in contact with the first lever exceeds a dead point at which an axial center of the second rotation axis and an axial center of the roller are arrayed just before inputting of the movable contact, the movable contact is made to be displaced in the first rotation axis direction as it approaches the input position.