Game system and jackpot lottery device that constitutes same

To ameliorate the sense of unfairness that players can have when game devices that participate in a jackpot lottery are divided into multiple groups and independent jackpot lotteries are held in each group, a jackpot lottery device performs grouping processing that links each of 4 or more game devices according to specified grouping conditions to at least one of multiple groups, and performs jackpot lottery processing by group for each of the multiple groups to determine the winning game device that wins the jackpot prize from among the game devices affiliated with that group. With this lottery processing, the winning frequency becomes higher for game devices with more tokens, wherein the cumulative number of tokens paid in by group when the jackpot lottery is won increases. The aforementioned grouping processing is performed each time specified group change conditions are met.