To provide a board surface structure of a game machine, which ensures flexibility in designing of a playfield when the size of various devices such as a performance display device or the like is increased.

The playfield 110 is formed by enclosing with a plurality of rail members. A display device 150 is fixed on a lower part on the opposite side of a guide passage 106 with an outlet 121 as a boundary in a manner to protrude to a front side from a game surface 102. A bottom surface of the playfield 110 is partitioned by a bottom surface rail 151 fixed along an inclined surface 150a of the display device 150 and an inner rail 105 separating the guide passage 106 from the playfield 110. An inclined angle of the bottom surface rail 151 is formed to be more gentle than that of the inner rail 105. The bottom surface rail 151 has a protruding region 151a which protrudes to be closer to the side of the outlet 121 than an inclined surface 150a being an upper surface of the display device 150, and the protruding region 151a is made to approach above a lower end 105b of the inner rail 105.