A developer container (30) includes a container body (31) and a movable wall (34). The container body (31) includes an inner surface (31K) defining a cylindrical internal space (31H) extending in a longitudinal direction, and a developer discharge port (319). The developer discharge port (319) is formed in a lower part of the inner surface (31K). The movable wall (34) includes an outer surface (34K) disposed slidably in contact with the inner surface (31K) of the container body (31), and a conveying surface (340S). The conveying surface (340S) defines a storage space (31S) for containing developer in cooperation with the inner surface (31K). The movable wall (34) moves in the longitudinal direction from one end side toward the other end side while conveying the developer in the storage space (31S) to the developer discharge port (319).