A developing device includes a developing container for accommodating a two-component developer; a developer bearing member for bearing and conveying the developer, a fixed magnet including a release pole for releasing the developer from the developer bearing member, being fixed to the inside of the developer bearing member; and a backflow prevention member that is a sheet-shaped member disposed along the entire length in the longitudinal direction of the developer bearing member so as to be upstream in the direction of rotation of the developer bearing member as viewed from the release pole, the backflow prevention member being disposed so that a proximal end portion thereof is fixed to an inside surface of the developing container, and a distal end portion thereof is in contact with or adjacent to the developer bearing member and facing downstream in the direction of rotation of the developer bearing member.