Abstract: A compact and inexpensive refractory monitoring temperature sensor and a compact and inexpensive refractory erosion location measuring device which can effect continuous detection of erosion over a wide range and specification of a location of an erosion and further can be re-used and used continuously. The temperature sensor includes at least two metal members and an insulating substance (2) filled between the metal members. The sensor detects a condition of an erosion of a refractory not from a melting breakdown of the sensor but from a variation in insulation resistance of the insulating substance which arises from a high temperature of the refractory due to erosion of the refractory. The measuring device incorporates such temperature sensor and discriminates an amount and a location of erosion of the refractory from a variation in insulation resistance between the metal members.