A breaker includes a contact unit provided in an airtight container. The contact unit has fixed contact points and a movable contact point which selectively contacts with the fixed contact points. Further, the breaker include a movable shaft having a part projecting outward from the airtight container, for moving the movable contact point to and from the fixed contact points, and a metal member for ensuring airtightness of the airtight container. The metal member has one end fixed to the airtight container and the other end fixed to the movable shaft and is extensible and contractible in accordance with the movement of the movable shaft. Moreover, the breaker includes a lever unit for moving the movable shaft between a closed position where the movable contact point is in contact with the fixed contact points and an open position where the movable contact point is separated from the fixed contact points.