1. An image processing method for generating and outputting an image of a virtual space, comprising: a first acquisition step of acquiring a position and orientation of a viewpoint of an observer; a second acquisition step of acquiring a position and orientation of a physical object having a movable part; an acquisition step of acquiring a moving amount of the movable part; a moving step of moving a part, corresponding to the movable part, of a virtual object which represents the physical object based on the moving amount; a generation step of generating an image which is seen when the virtual object, the part corresponding to the movable part of which is moved in the moving step, is observed from the viewpoint, based on the position and orientation of the viewpoint of the observer and the position and orientation of the physical object; and an output step of outputting the image generated in the generation step.