For the patients suffering from a paralysis of body, drawing on computers is widely used as an occupational therapy. In this paper, a drawing-aid system based on a fuzzy scheme is proposed. The proposed system compensates involuntary motions of cursor in mouse operations on computers. Different from conventional methods, the proposed method smoothes out involuntary motions of mouse cursor by using the weight functions which are determined by the supervised learning based on a fuzzy scheme. Although the conventional methods have difficulty in reducing the influence of sudden move, the proposed method can eliminate it without preliminary experiments. The validity of the proposed algorithm is confirmed through simulations.