A method of monitoring the surface temperatures of wafers in real time by measuring them according to the present invention monitors the surface temperatures of a polishing pad in real time by measuring them, and can thus actively deal with irregular variations in temperature on the surface of the wafer attributable to chemical reaction and friction in the process of cleaning the wafer. A sensor for measuring the surface temperatures of a wafer according to the present invention can be used in an environment in which there is fume generated from a cleaning solution, and is responsible for temperatures at respective points of an infrared camera and allows the correction of temperatures in respective sections.