A cartridge mountable to a main assembly of an electrophotographic image forming apparatus including a rotatable engaging portion, in a mounting direction substantially perpendicular to a rotational axis of the engaging portion, said cartridge comprising: a rotatable member for carrying a developer; and a rotatable coupling member (86; 286; 386) including a free end portion (86a; 286a) having projections (86d1, 86d2; 286d1, 286d2; 386d1, 386d2), said coupling member (86; 286; 386) being inclinable relative to a rotational axis of said rotatable member, wherein a number of said projections (86d1, 86d2; 286d1, 286d2; 386d1, 386d2) that have force receiving portions (86e1, 86e2; 286e1, 286e2; 386e1, 386e2) for receiving a rotational force from the engaging portion is two, and said force receiving portions (86e1, 86e2; 286e1, 286e2; 386e1, 386e2) of said two projections (86d1, 86d2; 286d1, 286d2; 386d1, 386d2) are disposed at substantially point symmetry positions with respect to a rotational axis of said coupling member (86; 286: 386), wherein a first inclinable angle (θ1) of said coupling member (86; 286; 386) with respect to the rotational axis of said rotatable member in a state that an imaginary line connecting said two projections (86d1, 86d2; 286d1, 286d2; 386d1, 386d2) is perpendicular to the mounting direction when said cartridge is moved relative to the main assembly in the mounting direction is smaller than a second inclinable angle (θ2) of said coupling member (86; 286; 386) with respect to the rotational axis of said rotatable member in a state that an imaginary line connecting said two projections (86d1, 86d2; 286d1, 286d2; 386d1, 386d2) is parallel with the mounting direction as seen in a direction of the rotational axis of said rotatable member when said cartridge is moved relative to the main assembly in the mounting direction, wherein an urging member urges said coupling member (86; 286; 386) to incline so that said free end portion (86a; 286a) of said coupling member (86; 286; 386) is moved in the mounting direction. a rotatable member for carrying a developer; and a rotatable coupling member (86; 286; 386) including a free end portion (86a; 286a) having projections (86d1, 86d2; 286d1, 286d2; 386d1, 386d2), said coupling member (86; 286; 386) being inclinable relative to a rotational axis of said rotatable member, wherein a number of said projections (86d1, 86d2; 286d1, 286d2; 386d1, 386d2) that have force receiving portions (86e1, 86e2; 286e1, 286e2; 386e1, 386e2) for receiving a rotational force from the engaging portion is two, and said force receiving portions (86e1, 86e2; 286e1, 286e2; 386e1, 386e2) of said two projections (86d1, 86d2; 286d1, 286d2; 386d1, 386d2) are disposed at substantially point symmetry positions with respect to a rotational axis of said coupling member (86; 286: 386), wherein a first inclinable angle (θ1) of said coupling member (86; 286; 386) with respect to the rotational axis of said rotatable member in a state that an imaginary line connecting said two projections (86d1, 86d2; 286d1, 286d2; 386d1, 386d2) is perpendicular to the mounting direction when said cartridge is moved relative to the main assembly in the mounting direction is smaller than a second inclinable angle (θ2) of said coupling member (86; 286; 386) with respect to the rotational axis of said rotatable member in a state that an imaginary line connecting said two projections (86d1, 86d2; 286d1, 286d2; 386d1, 386d2) is parallel with the mounting direction as seen in a direction of the rotational axis of said rotatable member when said cartridge is moved relative to the main assembly in the mounting direction, wherein an urging member urges said coupling member (86; 286; 386) to incline so that said free end portion (86a; 286a) of said coupling member (86; 286; 386) is moved in the mounting direction.