Summary A new instrument has been developed and is now in use on shop floor for inspecting chatter marks sometimes generated by the grinding and the ultra-precision machining process. The instrument is able to measure both geometrical waviness and fluctuation of glossiness of the finished surface. The instrument principally consists of an optical lever and phototransistor and detects two analogue signals separately, corresponding to local deviations of the surface inclination and the glossiness. The detected surface inclination signal that contains influence of the glossiness deviation is then processed by a computer for delineating the true height variation, namely waviness, of the measured surface. Analyses are demonstrated on test samples finished by the grinding and the ultra-precision machining process. The instrument is capable of analysing surfaces finished to 0.1 μm waviness or even less.