PURPOSE: To provide the simplified and low-priced cleaning device to be interlocked with a game machine without requiring various kinds of additional devices by arranging grinding cloth with a small gap between parallelly with a conveyer for conveying a prize winning medium above this conveyer when cleaning the prize winning medium of the game machine.

CONSTITUTION: The prize winning media of the game machine such as coins 2, for example, are moved from a collector to a conveyer 1 and conveyed one by one. Besides, grinding cloth 3 is arranged above the conveyer 1 with the small gap between parallelly to this conveyer 1. Further, the grinding cloth 3 is moved while being wound between a pair of pulleys 4, and pressed with the coin 2 on a pressing board 5 arranged on its upper surface. At such a time, the pressing board 5 is horizontally vibrated so that the grinding cloth 3 can be also vibrated to grind the one side of the coin 2. Successively, the coin 2 which one side is ground is dropped from the end terminal of the conveyer 1 through an internal passage 7 of a moving pipe 6 and moved onto another conveyer 8. Then, the other side of the coin 2 is ground by the similar operation.