This invention provides a wafer-type temperature sensor capable of eliminating the need for an A/D converter, adapting itself to automation and improving the heat resistance to measure temperature distribution of the upper surface of a wafer, a temperature measuring device using the sensor, a thermal processor having a temperature measurement function and a temperature measurement method. The wafer-type temperature sensor comprises a wafer and a plurality of temperature sensors arranged in regions which are formed by segmenting the upper surface of the wafer into a plurality of regions. Each of the temperature sensors includes an oscillation circuit for oscillating a frequency signal corresponding to the temperature of its own region within a frequency band that is different for every region in response to input of power supply voltage.