holder 54 a as shown in fig6 two throughholes 47 of rectangular cross section are formed in the bracket 46 a through which the projection 57 can pass the width of the throughhole 47 is formed slightly less than the width of the base end of the flat spring shaped member 57 a the projection 57 is pushed into the throughhole 47 by deforming the base end of the member 57 a towards the inside the flat spring shaped member 57 a which was pushed into the throughhole 47 then returns to its original shape and the base end projects outside the throughhole 47 thereafter the base end of the member 57 a comes in contact with the bracket 46 a surrounding the throughhole 47 if a pulling force is applied to the member 57 a and provides a resistance to any force tending to pull out the projection 57 moreover when the projection 57 is pushed into the throughhole 47 the legs 58 elastically deform outwards from the position of the broken line to the state shown by the solid line in fig6 the holder 54 a is thus firmly fixed to the bracket 46 a by the base end of the member 57 a and the elastically deformed legs 58 which grip the bracket 46 a the holder 54 b is fixed to the inverter housing 40.