A developer replenishing device includes a container mount to hold a developer container to contain developer used in image formation, an installation completion detector to detect completion of installation of the developer container in the container mount, a replaceable containing portion to contain developer, a conveyance channel to which the containing portion is removably connected and through which developer is transported from the developer container held in the container mount to the containing portion, and a conveyance pump to transport developer from the developer container through the conveyance channel to the containing portion. In a state in which the developer container is not held in the container mount according to a detection result by the installation completion detector, the conveyance pump transports developer from the conveyance channel to the containing portion.
