An engine generator, sufficiently meeting a demand for a simple configuration and easy control, is provided. The output of a generator 1 connected to an engine 2 is output through a rectifier circuit 3 and an inverter 4. The generator 1 is a dual-purpose generator both for a generator function and for an electric motor function, and is driven by a drive inverter as an engine starting electric motor. A DC—DC converter 5 is provided between the output side of the rectifier circuit 3 and the output terminal of a battery 6. The generator 1 is driven as an engine starting electric motor, using the battery 6 as a power supply, when the engine is started.