PURPOSE: To prevent a toner from flowing out or scattering to the outside, by link-detaining one end of an opening part of a receiving device to a machine frame by a spring, providing a lock member being movable to the left and right against the spring, and constituting so that the other end of the lock member is pushed aside to the left by the lower end of a toner vessel and is installed, and after the installation, the lock member moves to the right and is locked, and the lock is released manually after supply of a toner is ended.

CONSTITUTION: As for an opening and closing cover 23, the reverse side of an upper cover 21 and the upper face of the opening and closing cover 23 are made to contact closely at each circumferential edge part by a push-up spring A222, and opening parts 211, 221 are locked to a closed cover state by the opening and closing cover 23. When loading a toner vessel unit 1, it is inserted by moving a lock knob 263 to the left, and when a hand is set free, a lock member 26 is reset to the right by a compression spring 234, and the vessel unit 1 is held exactly. Also, the lock is released by loading the vessel unit 1, and a knob 25 can be moved to the right direction. When the opening and closing cover 23 moves to the right, the lock member 26 is fixed, therefore, a misoperation can be prevented. When the lock knob 263 is moved to the left against the compression spring 234, a lock pawl member 261 engaged to a mouth piece part 13 of the vessel unit 1 is shunted to the left, and the vessel unit 1 can be taken out of the opening part 211.