A cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus including a main assembly side rotatable engaging portion, wherein said cartridge is demountable to an outside of said apparatus main assembly after movement in a predetermined direction substantially perpendicular to a rotational axis of the main assembly side rotatable engaging portion, said cartridge comprising: (i) a rotatable member which is rotatable carrying a developer; (ii) a rotatable rotational force transmitted member (87; 287; 487) which includes an accommodating portion (87i; 287i; 487i) at inside thereof and to which a rotational force to be transmitted to the rotatable member is transmitted; (iii) a rotatable coupling member (86; 386; 486) including, (iii-i) a free end portion (86a; 386a) having a rotational force receiving portion (86e1-e4; 486e1-e4) configured to receive the rotational force from the main assembly side rotatable engaging portion, (iii-ii) a connecting portion (86c; 386c; 486c) which is connected with said rotational force transmitted member (87; 287; 487) and at least a part of which is accommodated in said accommodating portion (87i; 287i; 487i) so that a rotational axis (L2; L32; L42) of said coupling member (86; 386; 486) is pivotable relative to a rotational axis of said rotational force transmitted member (87; 287; 487) to permit said rotational force receiving portion (86e1-e4; 486e1-e4) to disengage from the main assembly side rotatable engaging portion with a movement of said cartridge in the predetermined direction, (iii-iii) a through-hole (86b; 386b; 486b) penetrating said connecting portion (86c; 386c; 486c); and (iv) a shaft portion capable of receiving the rotational force from said coupling member (86; 386; 486) and penetrating said through-hole (86b; 386b; 486b), characterized in that said shaft portion is supported by said rotational force transmitted member (87; 287; 487) at opposite end portions thereof so that said coupling member (86; 386; 486) is prevented from disengaging from said rotational force transmitted member (87; 287; 487) while permitting the pivoting of said coupling member (86; 386; 486) with respect to said rotational force transmitted member (87; 287; 487) and said shaft portion. (i) a rotatable member which is rotatable carrying a developer; (ii) a rotatable rotational force transmitted member (87; 287; 487) which includes an accommodating portion (87i; 287i; 487i) at inside thereof and to which a rotational force to be transmitted to the rotatable member is transmitted; (iii) a rotatable coupling member (86; 386; 486) including, (iii-i) a free end portion (86a; 386a) having a rotational force receiving portion (86e1-e4; 486e1-e4) configured to receive the rotational force from the main assembly side rotatable engaging portion, (iii-ii) a connecting portion (86c; 386c; 486c) which is connected with said rotational force transmitted member (87; 287; 487) and at least a part of which is accommodated in said accommodating portion (87i; 287i; 487i) so that a rotational axis (L2; L32; L42) of said coupling member (86; 386; 486) is pivotable relative to a rotational axis of said rotational force transmitted member (87; 287; 487) to permit said rotational force receiving portion (86e1-e4; 486e1-e4) to disengage from the main assembly side rotatable engaging portion with a movement of said cartridge in the predetermined direction, (iii-iii) a through-hole (86b; 386b; 486b) penetrating said connecting portion (86c; 386c; 486c); and (iii-i) a free end portion (86a; 386a) having a rotational force receiving portion (86e1-e4; 486e1-e4) configured to receive the rotational force from the main assembly side rotatable engaging portion, (iii-ii) a connecting portion (86c; 386c; 486c) which is connected with said rotational force transmitted member (87; 287; 487) and at least a part of which is accommodated in said accommodating portion (87i; 287i; 487i) so that a rotational axis (L2; L32; L42) of said coupling member (86; 386; 486) is pivotable relative to a rotational axis of said rotational force transmitted member (87; 287; 487) to permit said rotational force receiving portion (86e1-e4; 486e1-e4) to disengage from the main assembly side rotatable engaging portion with a movement of said cartridge in the predetermined direction, (iii-iii) a through-hole (86b; 386b; 486b) penetrating said connecting portion (86c; 386c; 486c); and (iv) a shaft portion capable of receiving the rotational force from said coupling member (86; 386; 486) and penetrating said through-hole (86b; 386b; 486b),