WJ-MS2-H, a magnet sensor for the temperature of -20~+180℃, has the switch with AC & DC 250V 1A built in so that it has no need of operation power. This sensor is operated with MAGNET WJ-MG4-H and uses the special cable for chemical resistance and heat resistance. Therefore, this product is available in poor circumstances including high temperature and moisture, dust, oil, and gas. A magnet line shield device (utility model patent) is attached to the both sides of the product for improving operation precision.