With a structure in which a coupling member includes a sphere providing a center of inclination (pivoting), a rotational force transmitted member has an opening have a diameter smaller than that of the sphere, and the coupling member is prevented from disengaging from rotational force transmitted member by contact of inner edge of the opening to the sphere, the inner edge of the opening may limit an inclinable (pivotable) angle range of the coupling member.In a state that a pin 88 which is a shaft portion is inserted in a hole 86b which is a through-hole provided in a coupling member 86, opposite end portions of the pin 88 are supported by a driving side flange 87 which is a rotational force transmitted member.The coupling member 86 and the driving side flange 87 and the pin 88 are connected in this manner, and the pin 88 contact the inside of the hole 86b without limiting the inclinable (pivotable) angle range, by which the coupling member 86 is prevented from disengaging from the driving side flange 87.