A sealing member for sealing a toner discharge opening of a toner
accommodating container detachably mountable to an image forming
apparatus, the sealing member includes a locking portion for being locked
with a portion to be locked provided in the image forming apparatus, the
locking portion being adapted to displace with a relative closing
movement relative to the portion to be locked, wherein the toner
discharging opening is brought into an open state from a closed state by
relative to movement of the sealing member relative to the toner
accommodating container with the locking portion being in engagement with
the portion to be locked; and a releasing force receiving portion for
receiving from the image forming apparatus a releasing force for
releasing engagement between the locking portion and the portion to be
locked by displacing the locking portion.