A wiper seal is less in sliding resistance that is encountered when the seal slides over a raceway surface of a guide rail, better in wear-proof quality, rich in durability, and further easy to steadily install it to a slider. The wiper seal is installed on one end of the slider in a linear motion guide system to wipe away foreign materials adhered on the guide rail. The wiper seal is made of polyester polyurethane foam having a reticular skeleton texture of three-dimensional construction including open-cells therein, the polyester polyurethane foam being squeezed or compressed into from ¼ to 1/20 in thickness to form a compact blank of three-dimensional construction having porosity therein. The wiper seal is set to come into sliding contact with the guide rail 1 to exert a positive interference of from 0.1 mm to 0.05 mm.