An interlock device includes an upper lid provided such that an inverter unit cannot be exposed and having a shape accommodating a housing, an interlock detecting terminal electrically connected to the housing when being in contact therewith and electrically disconnected from the housing when losing contact therewith, a bolt for fixing the upper lid to the housing, and a bracket for restricting a motion of the bolt for removal of the upper lid when the interlock detecting terminal is in contact with the housing.