PURPOSE: To provide a temperature sensor which can obtain an improved response depending on the mounting position relationship and its mounting method.

CONSTITUTION: The temperature sensor consists of a sheet-shaped thermistor element 2 which can output an electrical output equivalent to temperature by measuring temperature, an electrode and a connection wire 7 for taking the output from a temperaturemeasuring element 2, and a housing 6 for mounting the above element 2 to a cladding body. Also, the housing 6 allows the temperature-measuring element 2 to be mounted to the cladding body so that the angle between the longer direction of the section of the sheet-shaped temperature-measuring element 2 and a flow direction 10 of gas flowing in the cladding body is 45 degrees or less.