An electric wire lead-in part structure (15) includes: a conductor insertion hole (16) formed through a wall part (2Ca) of an inverter accommodating chamber; a conductor member (17) made of an electrically conductive material and inserted into the conductor insertion hole (16) in a waterproof manner and also, electrically conducted to the conductor insertion hole (16) and holding a power supply cable (11) passed therethrough; a shield grounding part (50) for electrically conducting a shield part (45) of the power supply cable (11) to the conductor member (17) at a position where the conductor member (17) is provided; and an electric wire waterproofing part (40) for waterproofing a gap between the conductor member (17) and the power supply cable (11). The shield grounding part (50) is configured to fasten a set screw (52) abutted against a crimp ring (55) provided on the shield part (45), the set screw (52) being threadedly engaged with the conductor member (17) so as to protrude into an electric wire passing hole (23) formed in the conductor member (17), across the axial direction of the electric wire passing hole (23).