An inverter device includes a rectifier circuit that rectifies alternating-current power supplied from a main power supply and generates direct-current power, a control power supply circuit that generates direct-current power for control using at least one of the generated direct-current power and direct-current power supplied from an external power supply, and a control unit that receives the generated direct-current power for control and performs a predetermined control operation. The control power supply circuit includes an insulation transformer including a primary side and second side winding wires, a first control power supply capacitor connected to the secondary side winding wire via a first diode, an external power supply capacitor connected to the first control power supply capacitor via a second diode and connected to a terminal, to which the external power supply is connected, via a third diode, and a second control power supply capacitor connected to the external power supply capacitor.