A powder collecting device for conveying toner, a developer, waste toner and/or a waste developer in a conveyance pipe in one direction and for dropping it into a container through an opening made at an end of the conveyance pipe. The container is mountable in a body of an image forming apparatus such that the end of the conveyance pipe is inserted into the container, and is dismountable therefrom. An elastic sealing member, which has a larger area than a cross-sectional area of the end of the conveyance pipe, is attached to a portion of the container through which the end of the conveyance pipe is inserted into the container. A plurality of cuts are made in the sealing member such that the sealing member has at least an upper flap having a longer elastically deformable portion and a lower flap having a shorter elastically deformable portion.