To generate a frame for providing a special service, to display a different game before throwing a ball in the frame and to easily generate winning by a desired probability.

A lucky frame is generated by prescribed conditions, the roulette screen of a desired winning generation probability is displayed before throwing the ball on a display 20 and the screen is stopped when a strike is generated. Also, a winning screen and a losing screen are prepared, the 100-ary numerical value less than one second of the timer is read at the time of detecting the pin arrival of the ball, the winning screen is displayed on the display 20 when the numeral is smaller than a set desired winning generation probability value and the losing screen is displayed in the other cases.