In order to measure temperature fields on tool face during cutting, a cutting tool with built-in thin film thermocouples (TFTs) has been devised. The TFTs composed of a nickel and nichrome thin films were fabricated on the rake face near the cutting edge of a sintered alumina tool insert using a physical vapor deposition and photolithography technique. An empirical formula that shows Seebeck coefficient of a TFT depends on electrical resistance of the TFT circuit was established. Three different types of tools in number and size of TFTs were developed and temperature fields on the rake face in cutting of a plain carbon steel S45C were measured. The results of the cutting thermometry experiment reveal that the devised tool with built-in three TFTs can measure temperature fields on the tool face and can sense slight change in cutting situation.