IN METAL CUTTING, IT IS A WELL-KNOWN FACT THAT THE VALUE OF Q/P, WHICH IS THE RATIO OF THE TANGENTIAL FORCE Q AND THE RADIAL FORCE P, IS REMARKABLY DIFFERENT IN MACHINING AND GRINDING. IN THIS PAPER, CONSIDERING MACHINING AND GRINDING COLLECTIVELY, INVESTIGATION ON THE EFFECTS OF BASIC FACTORS WHICH PRODUCE SUCH DIFFERENCES SYSTEMATICALLY WAS CARRIED OUT BY A SIMPLE MODEL EXPERIMENT. THE RESULTS OF THE EXPERIMENT MADE IT CLEAR THAT COMPARED TO MACHINING, IN GRINDING ALL VALUES OF BASIC FACTORS INCLUDING INTERFERENCE DEPTH OF CUTTING EDGE AND WORKPIECE, CUTTING SPEED, CUTTING EDGE CONDITION, ETC. ARE IN THE DIRECTION OF REDUCING THE CUTTING FORCE RATIO. MOREOVER, THE RESULTS SHOWED THAT THE FORCE RATIO IN GRINDING IS CONTROLLED BY THE PRODUCT OF THE INTERFERENCE LENGTH AND THE MAXIMUM INTERFERENCE DEPTH PER CUTTING EDGE OF ABRASIVE GRAIN.