A cartridge detachably mountable to a main assembly of an image forming apparatus, comprising: a rotatable member; a rotatable rotational force receiving member for transmitting a rotational force to be transmitted to said rotatable member; a preventing member (89, 189, 289, 389, 489) connected with said rotational force receiving member and including an accommodating portion (89b3, 289b3, 389b3) therein; a rotatable coupling member including a free end portion which includes a rotational force receiving portion (86e2) for receiving the rotational force and including a connecting portion connected with said preventing member (89, 189, 289, 389, 489) to be partly accommodated in the accommodating portion (89b3, 289b3, 389b3) so that a rotational axis of said coupling member permits tilting thereof relative to a rotational axis of said rotational force receiving member; and a shaft portion (88, 186a, 186b) capable of receiving the rotational force from said coupling member, the rotatable coupling member is tiltable relative to the shaft portion (88, 186a, 186b), wherein said preventing member (89, 189, 289, 389, 489) includes a supporting portion (89c, 189c1, 289c, 389c, 489c) for supporting one end of said shaft portion (88, 186a, 186b) so as to prevent said shaft portion (88, 186a, 186b) from moving in a rotational direction of said rotatable member, characterized in that the supporting portion (89c, 189c1, 289c, 389c, 489c) is configured to transmit the rotational force received from said shaft portion (88, 186a, 186b) via the supporting portion (89c, 189c1, 289c, 389c, 489c) to said rotational force receiving member, either said supporting portion (89c, 189c1, 289c, 389c, 489c) is a groove portion (89c, 189c, 389c, 489c) which opens at one end of said rotatable member with respect to an axial direction of said rotatable member, and said supporting portion (89c, 189c1, 289c, 389c, 489c) supports the one end of said shaft portion (88, 186a, 186b) so as to prevent said shaft portion (88, 186a, 186b) from moving toward the other end of said rotatable member with respect to the axial direction, or said supporting portion (289c, 489c) is a through hole (289c, 489c) surrounding an outer periphery of said shaft portion (88, 186a, 186b), and said supporting portion (89c, 189c1, 289c, 389c, 489c) supports the one end of said shaft portion (88, 186a, 186b) so as to prevent said shaft portion (88, 186a, 186b) from moving in an axial direction of said rotatable member. a rotatable member; a rotatable rotational force receiving member for transmitting a rotational force to be transmitted to said rotatable member; a preventing member (89, 189, 289, 389, 489) connected with said rotational force receiving member and including an accommodating portion (89b3, 289b3, 389b3) therein; a rotatable coupling member including a free end portion which includes a rotational force receiving portion (86e2) for receiving the rotational force and including a connecting portion connected with said preventing member (89, 189, 289, 389, 489) to be partly accommodated in the accommodating portion (89b3, 289b3, 389b3) so that a rotational axis of said coupling member permits tilting thereof relative to a rotational axis of said rotational force receiving member; and a shaft portion (88, 186a, 186b) capable of receiving the rotational force from said coupling member, the rotatable coupling member is tiltable relative to the shaft portion (88, 186a, 186b), wherein said preventing member (89, 189, 289, 389, 489) includes a supporting portion (89c, 189c1, 289c, 389c, 489c) for supporting one end of said shaft portion (88, 186a, 186b) so as to prevent said shaft portion (88, 186a, 186b) from moving in a rotational direction of said rotatable member, characterized in that the supporting portion (89c, 189c1, 289c, 389c, 489c) is configured to transmit the rotational force received from said shaft portion (88, 186a, 186b) via the supporting portion (89c, 189c1, 289c, 389c, 489c) to said rotational force receiving member, either said supporting portion (89c, 189c1, 289c, 389c, 489c) is a groove portion (89c, 189c, 389c, 489c) which opens at one end of said rotatable member with respect to an axial direction of said rotatable member, and said supporting portion (89c, 189c1, 289c, 389c, 489c) supports the one end of said shaft portion (88, 186a, 186b) so as to prevent said shaft portion (88, 186a, 186b) from moving toward the other end of said rotatable member with respect to the axial direction, or said supporting portion (289c, 489c) is a through hole (289c, 489c) surrounding an outer periphery of said shaft portion (88, 186a, 186b), and said supporting portion (89c, 189c1, 289c, 389c, 489c) supports the one end of said shaft portion (88, 186a, 186b) so as to prevent said shaft portion (88, 186a, 186b) from moving in an axial direction of said rotatable member.