Abstract: A breaker device is provided in which a lever can be locked in specified positions with an improved reliability and unlocking can be easily effected. A slider (60) carried by a lever (30) and a panel (22) of a casing (20) define a locking mechanism of the device. When the lever (30) is in a specified rotation position, the slider (60) and the panel (22) are engaged with each other to lock the lever (30) in that position. An unlock portion (62) for unlocking the locking mechanism is provided in a position to be covered by a handle portion (32) of the lever (30). Since this unlock portion (62) is protected by the handle portion (32), a tool or the like cannot come into contact with or strike the unlock portion (62). On the other hand, if a finger is placed on the handle portion (32) to rotate the lever (30), the tip of this finger is located at the underside of the handle portion (32), so that the unlock portion (62) can be easily operated.