To provide a developer replenishment container which efficiently performs higher-density filling of developer in time in the conventional manner using the conventional filling machine or grant of oscillation and allows developer filling of an amount which is not different from a completed state even at an incomplete state as the replenishment container for holding the developer.

In the developer replenishment container for replenishing the developer to an image forming apparatus main part, it has a container frame having a discharge port for discharging the developer and a filling opening for filling the developer to the developer replenishment container and a cover member for sealing the filling opening, the filling opening is provided with a flexible sheet member so as to rise from an edge of the filling opening and it is characterized that the flexible sheet member is held in the cover member and the container frame when the filling opening is sealed by attaching the cover member after filling the developer.