A developing apparatus includes a container containing a developing agent and having an opening; a developer bearing member provided at the opening of the container; a magnetic sealing member magnetically restricting leakage of the developing agent out of an end of the developer bearing member in a longitudinal direction of the developer bearing member the magnetic sealing member being formed at the end in the longitudinal direction of the developer bearing member as extending along a circumferential direction of the developer bearing member; a sheet member preventing the developing agent from leaking out of the opening of the container, the sheet member being attached along the longitudinal direction of the container forming the opening, the end in the longitudinal direction of a free end of the sheet member entering in a space between the developer bearing member and the magnetic sealing member; and an auxiliary member holding a free end side of the sheet member around the magnetic sealing member. The container is formed with, at a portion attaching to the sheet member, a recess into which the auxiliary member enters.