The purpose of this study was to develop a method for rapid on-machine measurement of surface roughness, which can rapidly obtain the surface roughness of a workpiece rotating as fast as in the grinding process and allow total surface roughness inspection of ground workpieces on machine tools. A new method involving measurement of surface roughness using the thermoelectric effect is proposed and the feasibility of rapid on-machine measurement was verified by investigation of measuring characteristics of the developed system. The surface roughness could be obtained from the electromotive force, which is generated as soon as the developed sensor using thermocouple wires makes contact with the workpiece rotating on the machine. The measurement can be done even if the workpiece is rotated at a peripheral speed about 2000 times larger than the usual trace speed of conventional surface roughness testers.