To provide a fixing structure for a game board in a pachinko game machine capable of smoothly replacing the board without the need for correcting "irregularly skipping ball" caused by relative positional relation between an outer rail and a launching rail at the time of replacing the board of an old model with that of a new model.

When the game board 15 is mounted onto a front frame 1, the game board 15 having an inner rail, accessories and the like thereon and an outer rail support frame 20 having an outer rail 35 alone are fixed to the front frame 1 by fitting respective positioning holes 16 and 28 thereof onto their corresponding positioning pins 5 on the front frame 1, and thereafter engaging the hooking recesses 47 of metal fittings 45 serving as hooking means with the hooking grooves 6 of the positioning pins 5 projecting through the outer rail support frame 20.