DRIVING FORCE TRANSMISSION APPARATUS

A driving force transmission apparatus (2) includes: a housing (20) having an inner peripheral spline portion (210); an inner shaft (23) having an outer peripheral spline portion (230); a main clutch (3) including first outer and inner clutch plates (31, 32) respectively engaged with the inner and outer peripheral spline portions (210, 230); a cam mechanism (4) generating pressing force for pressing the main clutch (3) by relatively rotating a pair of cam members (41, 42); and an electromagnetic clutch mechanism (5) including an armature (50) engaged with the inner peripheral spline portion (210) and applying rotation force to the cam mechanism (4) for relatively rotating the cam members (41, 42) through energization of an electromagnetic coil (53). An end face (212a) facing the armature (50) is formed in the inner peripheral spline portion (210) between a first region (210a) engaged with the first outer clutch plate (31) and a second region (210b) engaged with the armature (50). Movement of the armature (50) toward the first region (210a) is regulated by contact of the armature (50) with the end face (212a).