To prevent an improper game deed using an improper substrate.

A CPU of a game control means executes a plurality of start port switch processings S15a, S15b, S15c in a main processing. In the start port switch processings S15a, S15b, S15c, the CPU judges an occurrence of a start winning when the start port switch is continuously turned on a plurality of times. Also, the CPU takes in a value of an external random number generating means which changes values at a high speed based on the on-information of the start port switch, and makes the value a big winning judgement value.