To provide an attachment/detachment facilitating mechanism which improves operability at the time of attaching and detaching a game board.

A game machine is provided with a front frame assembled to an outer frame 10 so as to be opened and closed on the side, the game board housed and held in a housing frame on a front frame back surface side, and a back set board 40 assembled to the back of the front frame. The game board is housed so as to be opened and closed on the side at the back and attached and detached by a game board hinge mechanism provided on the housing frame and the game board, and the back set board 40 is assembled so as to be opened and closed on the side at the back of the front frame by a back set board hinge mechanism provided on the front frame and the back set board. The outer frame 10 and the back set board 40 are provided with an engaging connection structure 70 for locking and holding the back set board 40 in an open posture by the vertical engagement of a member 72 to be locked provided on the back set board and a locking member 71 provided on the outer frame at the time of pressurizing the back set board 40 to the outer frame in the state of opening the front frame to the front and opening the back set board to the back of the front frame.