Three-dimensional image processing has two processes. In a first process, a three-dimensional space including only a horizon appears on a display screen. By drawing a stroke line in the space, a wall having the stroke line as the base line is set as a canvas. A picture drawn by a user is mapped onto the canvas, resulting in a three-dimensional picture. By repeatedly setting the canvases and pictures, a desired scene can be constructed. A desired three-dimensional scene can further be obtained by rotating the canvas or moving the viewing point. In a second process, the base line of the canvas is constantly displaced between a first curve, a second curve, and an interpolation curve. The three-dimensional image pasted on the canvas is moved in accordance with the movement of the canvas. Thus, it appears to the user that the three-dimensional image is animating.