PURPOSE: To reduce the cost of temperature sensor through downsizing and simplification by a constitution wherein the variation of resistance due to the temperature variation of a thin metallic film having high temperature coefficient is detected by means of three resistors having low temperature coefficient.

CONSTITUTION: A metallic thin film element 11 is formed by laminating a metallic thin film of permalloy NiFe and a protective film in stripe on a glass plate so that the element 11 exhibits relatively high temperature coefficient in measuring region. Three resistors 13-15 are connected to constitute a bridge circuit 12 along with the element 11. Carbon film resistors having low temperature coefficient, for example, are employed as the resistors 13-15. An external power supply 16 is connected with one set of opposing joints 12a, 12b of the circuit 12 and the other set of joints 12c, 12d are arranged oppositely thereto. When a temperature variation to be measured is imposed on the element 11, resistance thereof varies to produce potential difference between the terminals 12b, 12c. The potential difference is detected and processed thus detecting the temperature variation of the element 11 and the temperature to be measured.