An arc runner has a pair of side panels covering movable contacts and fixed contacts from a width direction of a movable contactor, a back panel covering the movable contacts and the fixed contacts from a longitudinal direction of the movable contactor, and a top panel covering the movable contacts and the fixed contacts from above, is formed of a magnetic material, and guides arcs to be generated between the movable contacts and the fixed contacts when the movable contacts and the fixed contacts separate from each other, toward an upward direction of the movable contactor. Furthermore, the arc runner includes, in a central portion of the top panel, a top panel hole flow-path area which is larger than top-panel to side-panel gaps formed between the side panels and the top panel.