Thermoelectromotive force between the tool and the workpiece has been measured for estimating the cutting temperature. However, there is no example of thermoelectromotive force measurement application of detecting tool wear or damage on production sites. In this research, thermoelectromotive force is measured in practical machining conditions with a simple measuring method. The experimental results in the end milling process show that the measured thermoelectromotive force can be used to infer the tool edge damage.