To solve a problem that, in a magnetron power source device, when an inverter type to send power by high frequency is adopted, constant current control cannot be made if a choke coil is incorporated in a circuit, and it becomes unstable to make the system also unstable.

The magnetron power source device incorporates an inverter including a power switch and a pulse transformer and a magnetron oscillator. A coil element and a resistor element in parallel to the coil element are incorporated on a ground side or high voltage side of the magnetron oscillator, and furthermore, a varistor is incorporated in parallel to the coil element and the resistor element.