In many manufacturing systems, the role of skilled operators has been reduced down together with the progress of automatization technology. In some industries, however, the superiority of the manual operation to fully-automated system is reappraised recently. It is difficult to eliminate manual operations entirely from all manufacturing processes, because sophisticated sensitivity of human operators is indispensable in some kind of process. In this case, the characteristics of the sensitivity should be investigated in detail for utilizing it efficiently. In this research. the authors aim at clarification of manual machine tool operation from the viewpoint of human engineering. Particularly, minute grooving operation with a lathe. in which operational accuracy and speed are dependent upon the perception of the operator, is discussed in the present paper. Firstly, an experimental apparatus “virtual lathe” is newly developed so that analyses may be done under simplified conditions. By using it, the operator gets cutting force, motion of cutting tool, cutting sound, etc. through his own perceptive organs as if he uses an actual machine. Applying the apparatus to the minute grooving, secondly, the skill learning process of six testees is investigated. Obtained conclusions are summarized as follows : The similarity between actual operation and virtual lathe operation is confirmed. The force sensory feedback is effective in improvement of learning speed. The skill acquired relevant to operating accuracy is difficult to lose compared with that relevant to operating speed.