To carry out a lottery by obtaining a random number whose occurrence probability is distributed uniformly and which does not generate correlation with another random number, in a pinball game machine.

In the pinball game machine, a detector for detecting passing through of a game medium is provided at a discharging port (outlet) which accepts game mediums which are nor accepted into any prize-winning port. When the detector detects the game medium, a random number to be output by a random number generator (counter) is obtained, and the obtained random number is stored in one of a plurality of array areas of an array storage part. In the case of carrying out the lottery, one of the plurality of array areas of the array storage part is selected to read the random number stored in the array area, and presence/absence of prize-winning and the kind of prize-winning are judged based on the read random number.