A game device capable of ensuring player's action to be displayed in a judgment area set in a player image is provided. A game device (10) including a player image acquisition unit (60) for sequentially acquiring a player image representing the player, a game processing unit (72) for controlling a game based on an amount of action of the player displayed in the judgment area set in the player image further includes an action range image production unit (62) for producing an action range image representing an action range of the player based on the player image sequentially acquired by the player image acquisition unit (60), and a judgment area setting unit (68) for setting the judgment area in accordance with the content of the action range image produced by the action range image production unit (62).