A toner container detachably mountable to an image forming apparatus, includes a main body for containing toner; a sealing portion for sealing the toner discharge opening; locking projections for snap-fitting engagement with holes provided in a cylindrical member of an image forming apparatus, wherein the projections receive from the cylindrical member unsealing forces for unsealing the toner discharge opening by a relative movement between the sealing portion and the toner container, wherein a number of the locking projections is larger than a number of ribs provided between the holes of the cylindrical member.