A developing frame which can improve a sealing property for developer at the end portion of a developing roller. The developing frame has a first frame member having a developer supplying opening provided to supply a developer from a developer containing portion containing the developer to a developing area, a second frame member joined to the first frame member by molten resin, an attachment portion, a seal member for preventing the developer from leaking from the lengthwise end portion of the developing roller being attached to the attachment portion, and a resin reservoir depressed from the joint surface of the first frame member and the second frame member toward the attachment portion, and in which the molten resin is stored.