PURPOSE: To prevent foreign substances including water, etc., from penetrating to the inner parts of an engine and a generator, by disposing the engine overlappingly on the topside of the generator, while covering the upper part of the engine with a cover being larger in diameter than that of the generator.

CONSTITUTION: A crankshaft 3 of an engine 1 and a rotary shaft 31 of a generator 10 both are disposed coaxially along a vertical direction. In addition, the engine 1 is set up on the topside of the generator 10. Moreover, both the upper part and the side of the engine 1 are overlaid with a lidded cylindrical cover 36 being larger in diameter than that of the generator 10. Doing like this, penetration of foreign substances including water, fuel and the like into the inner parts of the engine 1 and the generator 10 can be prevented.