A toner supply container detachably mountable to an image forming
apparatus, includes a rotatable toner containing portion for containing
toner having a toner discharging portion projected from one end thereof,
with respect to a direction of a rotational axis, of the toner containing
portion, the toner discharging portion having a cross-sectional area,
which is smaller than that of the toner containing portion, and having an
opening, and which is formed in a peripheral portion thereof, for
permitting discharging of the toner; and a coupling member provided on
the end of the toner discharging portion, including a coupling engagement
portion engageable with a hole formed in a peripheral portion of a
cylindrical member provided in the image forming apparatus to receive a
rotational driving force for discharging the toner from the cylindrical
member, wherein the coupling engagement portion includes a rotational
force receiving projection having a side for receiving the rotational
driving force from a coupling rib at a circumferential end of the hole of
the cylindrical member, and is elastically deformable in a radial
direction so that the rotational force receiving the projection is
engaged with the hole of the cylindrical member.