To reduce the number of parts by driving an oil pump with a simple structure.

An oil pump 40 composed of an oil supplying pump 41 and an oil recovering pump 42 is disposed on a lien extended from a crankshaft 21, a joint member 24 disposed on an end part of the crankshaft and a joint member 44 disposed on an end part of a pump shaft 43 are joined in a cover 25 of a engine and on a same axial line, and a surface opposed to a driving transmitting surface in a projection part for forming a recessed and projected shaped joining part of both joint members is formed as an inclining surface for guiding a projection part of the joint member of a counterpart side. A crankshaft side joint member is fastened with an ACG rotor 23. An oil tank connected to the oil pump is disposed in the upper most vicinity of the oil pump.