1. A game machine comprising: a controller of a target, the target including at least four known points defining a plane; an image sensor having an image plane on which an image of the known points of the target are formed; a processor that calculates an attitude of the image plane relative to the plane defined by the known points of the target on the basis of the output of the image sensor including the information of the positions of the image of the known points on the image plane; and a signal generator that generates a signal to be transmitted to the controller to cause a change in the target depending on the attitude calculated by the processor.