Abstract: A slot machine of the present invention comprises: a mechanical reel device provided with a plurality of reels each having a plurality of symbols drawn on its peripheral face; an image display device which is provided at a front of the mechanical reel device and is capable of changing the state of the backside thereof from visible to invisible by displaying an image; and a controller, the controller programmed to execute the processing of: (A) executing a game in which the plurality of symbols are variably displayed and then stop-displayed to the mechanical reel device after game media are BET in number equal to or less than a previously set maximum number of BETs, and game media are paid out in number according to the plurality of symbols stop-displayed or a combination thereof; (B) shifting a mode from a non-insurance mode to an insurance mode on condition that a predetermined number of game media is inserted; (C) counting the number of games played after shifting to the insurance mode, in the insurance mod