A control circuit board (25) configuring an inverter (21) serves as a thermally-conductive substrate. One surface of the control circuit board (25) is installed in a heat transferable manner on a heat-dissipating planar part (31) disposed on a housing (2), while heat-producing electrical components (39) are disposed in a heat transferable manner on the other surface of the control circuit board (25). The control circuit board (25) includes a substrate body (41) constituted of an insulator, and heat-conducting through members (42) constituted of a good thermal conductor filled through in a thickness direction of the substrate body (41). One end of each of the heat-conducting through members (42) is disposed in a heat transferable manner on the heat-dissipating planar part (31), and the electrical component (39) is disposed in a heat transferable manner on the other end.