To discharge game balls stored within a ball box from an outlet on the bottom without being clogged, and to prevent fraudulence of insertion of a stick-like member, etc. into a game machine island from the outlet.

The game ball-storing box 30 for storing game balls acquired in a game machine 3 arrayed in the game machine island 1 is mounted on a counter 5 of the game machine island 1. The ball outlet 35 for discharging game balls is opened on the bottom face 31 of the box, and a dome-shaped cover 36 is disposed over the ball outlet 35 to cover the outlet. An intake 37 is disposed on a side of the cover 36 to let game balls stored on the bottom face 31 flow down to the ball outlet 35.