PURPOSE: To increase the distance travelable with a battery while suppressing the temporary influence on the output of a running motor at the time of starting an engine generator by lightening the temporary burden on the battery at the time of starting the engine generator.

CONSTITUTION: In a hybrid power supply for a motor running vehicle equipped with a battery 10 for driving a running drive source, i.e., a motor 14, and an engine driven generator 3 for feeding power to the battery 10, the generator is operated as a generator during operation of an engine 2 and the output from the generator is rectified through inverter units 21, 15 before being fed to the battery 10. At the time of starting the engine 2, a slowly rising voltage is applied from the battery 10 through the inverter units 21, 15 to the generator thus operating the generator as a motor for smarting the engine.