To provide an unconventional new game having reduced and frequent variation display times.

When a present game condition has a high probability (variable probability condition) and a blank is drawn in a jackpot lottery performed when a game ball enters a first special symbol-start pocket 126, a lottery is performed to determine whether or not the high probability condition is lowered to a normal probability condition. When winning the lottery, any of a game having reduced and frequent variation display times (e.g. 100 variation display times) which is advantageous to a player and a game having reduced and frequent variation display times (e.g. 50 variation display times) which is disadvantageous to the player is determined by a random number lottery, so that the determined game is performed.