Pinion-shaft support structure for starter in power unit

Object: To provide a pinion-shaft support structure for starter in a power unit which can firmly fix a pinion holder to a crankcase thereby ensure stable supporting of the pinion shaft. Means of Solution: In a case where one end of a pinion shaft (45) supporting a pinion (46) movably in an axial direction is supported with a bearing boss(48)which faces the inside of the transmission case(23) and which is formed in a crankcase (10), and the other end is supported with a boss (50a) of a pinion holder (50) provided in the transmission case (23), the pinion holder(50) is integrally fixed to the crankcase(10)with plural bolts (51) and (52) surrounding the boss (50a) at equal intervals.