A development device used for an image forming apparatus includes a frame member, a developer bearing member configured to develop a latent image formed on an image bearing member using developer, and an edge portion sealing member provided between an edge portion in a rotational axis direction of the developer bearing member and the frame member to prevent the developer from leaking to an outside of the development device from between the edge portion and the frame member, and including, in a state of being compressed between the edge portion and the frame member, a layer that includes an aggregate of a plurality of foam cells in which a foam cell communicating with an adjacent cell via a communication hole and a foam cell not communicating with an adjacent cell are mixed in a direction from an inside of the development device to the outside thereof.