PURPOSE: To make it possible to miniaturize an engine in the axial direction if the crank shaft by supporting the auxiliary drive shaft, to which a clutch for controlling the motive power transmitted to an auxiliary equipment is provided, in parallel with the crank shaft.

CONSTITUTION: Motive power is transmitted to an auxiliary equipment through an auxiliary drive shaft 14 supported on the body of an engine 11 in parallel with the crank shaft 13. The motive power to the auxiliary equipment is controlled by the hydraulic clutch 25 provided to the auxiliary drive shaft 14. For this reason the hydraulic clutch 25 is arranged axially and parallel to the crank shaft 13, and as a result the engine 11 can be miniaturized in the axial direction of the crank shaft 13. And the arrangement of the hydraulic clutch 25 in the space allowed between both ends of the auxiliary drive shaft 14 can also regulate letting the engine be getting large in size in the angle direction to the crank shaft 13. This can miniaturize the whole engine.