A toner bottle unit detachable to an image forming apparatus includes an opening/closing device for making an opening of a toner bottle by removing a cap from the opening and closing the opening by attaching the cap. An opening/closing operation device is provided to swing from an open position, in which the opening/closing device makes the opening, to close position, in which the opening/closing device closes the opening. The opening/closing device is operated to make the opening in conjunction with swinging movement of the opening/closing operation device from the close position to the open position, and closes the opening in conjunction with the swinging movement of the opening/closing operation device from the open position to the close position. The opening/closing operation device is swung between the open and close positions substantially around the central axis.