A cover accommodates a power converter receiving high voltage. A connector assembling portion to which a connector of an external power line is assembled is arranged external to the cover and secured by a securing member to a vehicle's main body. A support member is arranged at a lower surface of the cover and connector assembling portion, rather than that portion of casing connecting the connector assembling portion and the power converter's main body, between the cover and the connector assembling portion and thus binds them together.