A temperature sensor has a sensor tip and a front for measuring the temperature of the inner walls of tools, particularly inner walls of injection molding tools. The tip of the temperature sensor has two thermocouple wires of a thermocouple. Each thermocouple wire of the thermocouple guided to the front is welded to the sensor tip up to a depth which is larger than the total processing depth behind the front. The sensor tip is processable by removing of material at the front up to that processing depth.