To enable to generate high quality random numbers having high random characteristics by generating random numbers by a specified calculation using a random numbers generating means based on multiple initial values stored in an initial value storage, and sequentially storing the generated random numbers as new initial values.

In a variable display game by a special pattern display device, a control circuit 1 generates random numbers which are used to determine premiums and stop pictures, and an initial value storage means 2 is provided which stores multiple any values previously set as an initial value. A random numbers generating means 3 is also provided which generates random numbers by executing a specified calculation on multiple initial values stored. When a ball is put into a premium port, the random numbers generating means 3 generates random numbers, and the generated random numbers are sequentially stored as new initial values. Additionally, an interruption process is executed at specified intervals, and the random numbers generating means 3 generates new random numbers based on the multiple initial values stored in the initial value storage means 2.