An inverter unit includes a first circuit board and a second circuit board arranged at a predetermined space so as to face each other. Each of the first circuit board and the second circuit board has a main circuit forming area. A plurality of power devices are mounted in the main circuit forming area of the first circuit board and form a main circuit. A plurality of capacitors are electrically connected to the plurality of the power devices and mounted in the main circuit forming area of the second circuit board. A control circuit controls the operation of the main circuit. The second circuit board includes a control circuit forming area separated from the main circuit forming area. The control circuit includes a first control circuit formed in the control circuit forming area of the second circuit board.