To enhance the player's expectation on prize winning and interest on a game by exactly informing a player that a combination of symbols to be prize winning is varying.

When a ball gets into a starting prize winning port 14, reels 20a, 20b, 20c simultaneously start variable display of symbols. When the right and left reels 20a, 20c stop the variable display after a prescribed time to get into the Reach state (one step before completion of prize winning), a 'Complex Reach' in which the embodiment of the other reel 20d is orderly switched to plural kinds of embodiment to indicate different prize winning probabilities appears. A count display 18 displays the numeral count to show a prize winning rate properly changing display colors and, after a prescribed timing, the prize winning rate indicated by the final mode is fixedly displayed.