Developer container and image forming apparatus including the developer container with sealing mechanism providing enhanced usability

A developer container supplies developer to a development device and includes a storage, an opening, a first seal member, a through-hole, and a second seal member. The developer is supplied from the storage to the development device through the opening. The first seal member seals the opening and is pulled in a predetermined direction to unseal the opening. The through-hole guides the first seal member toward an opposite side of the opening. The second seal member is provided on at least one of a lead-in opening and a lead-out opening of the through-hole and elastically blocks the at least one of the lead-in opening and the lead-out opening. A non-bonded portion of the second seal member elastically blocks the at least one of the lead-in opening and the lead-out opening when the first seal member is pulled out from the through-hole through the non-bonded portion.