A developer storage container includes a container main body, an outflow port, an open/closed member and a turn stop part. The outflow port from which a developer flows out is formed in the container main body storing the developer. The open/closed member is supported to the container main body and, moves relative to the container main body based on a rotation of the container main body. The open/closed member opens and closes the outflow port. The turn stop part is formed on a wall face of the container main body, and has a circular arc shape being concentric with a rotation direction of the container main body. The turn stop part engages with a convex part which is provided in the attachment section and is formed at a different position in response to the image forming apparatus body.