Real space image including a simple prototype created based on three-dimensional CAD data is captured by an image input apparatus. A position/orientation measuring apparatus measures positions and orientations of the image input apparatus and simple prototype. An information processor captures position/orientation information representing the position and orientation of the simple prototype in the image captured by the image input apparatus 102. The information processor further extracts a hand area from an image, renders a three-dimensional computer graphic image on the simple prototype, excluding the extracted hand area, in the image based on the position/orientation information and the three-dimensional CAD data, and synthesizes the image and the three-dimensional computer graphic image. Here, the simple prototype has a different color from a color of the hand area.