A developer storage container (30) includes: a container body (31); a lid (32); a stirring member (34); and an input gear (36). The container body includes: a bottom portion (310); an opening (31P) extending in a longitudinal direction thereof; a first sidewall (31R) and a second sidewall (31L); and a storage space (30S) for storing developer therein. The second sidewall includes a bearing portion (312) disposed to face the storage space. The first sidewall includes: a shaft hole (313S) communicating between an outside of the container body and the storage space; and a support portion (313T) supporting a distal end of a coupling (342) of the stirring member from therebelow to prevent the stirring member from falling onto the bottom portion, in a state in which a distal pivot portion (341) of the stirring member is inserted into the bearing portion, and the coupling is disposed facing the shaft hole.