To make it possible to impart a more stimulative tension feel and expectation feel to a player by printing the one side surface of a transparent film base material with plural designs with ordinary ink, printing a light shielding part with light shielding ink and applying thermosensitive discoloring ink which is changed by temperature between the film base material and the light shielding part.

The reel belt 1 is formed by printing the one side surface of the transparent film base material 2 with the plural designs 3 with the ordinary ink, printing the light shielding part 5 with the light shielding ink and applying the thermosensitive discoloring ink 6 between the film base material 2 and the light shielding part 5. While the thermosensitive discoloring ink 6 maintains a dark color at ordinary temperature (the temperature in the machine), the ink is discolored translucent when the ink is heated from outside. When the reel belt 1 is heated by hot water, etc., the color of the light shielding ink applied to print the light shielding part 5 from outside is transmitted and the discoloration occurs in the coated part. If, for example, a big bonus approaches or occurs, a heating device is activated, by which the color of the entire part of the reel belt 1 of the part exclusive of the designs 3 is discolored.