© (2014) Trans Tech Publications, Switzerland. In superfinishing, a fine surface can be obtained by transiting the machining states from the cutting action to the finishing one. In this study, we propose an advanced machine control system in superfinishing. The superfinishing stone is retracted automatically when the proposed system detects improvement in the surface roughness of the workpiece. The suitable machining time is determined by monitoring the machining force ratio measured with a force sensor. With machining experiments, we confirm that the finished surface roughness can be controlled by adjusting the threshold value of the machining force ratio to retract the superfinishing stone during machining.