A game machine includes: an entertainment button that can move up and down from a normal operation position to a protruding position; a display part that displays characters associated with a game; a character determining part that determines a character to be displayed on the display part; a stopper plate that holds the entertainment button in the protruding position; a protruding position detecting part that detects the entertainment button being held in the protruding position by the stopper plate; a push operation detecting part that detects the entertainment button being pushed down; and a time interval measuring part that measures, when the protruding position detecting part detects the entertainment button being held in the protruding position, a time interval until the push operation detecting part detects the entertainment button being pushed since the protruding position detecting part no longer has detect the entertainment button being held in the protruding position.