In this investigation we tried to analyze the mechanism of evolution of abrasion of wire drawing die made of tungsten carbide for the purpose of finding the efficient lubricant or high-durable die for the abrasion.An apparatus for testing the abrasion of die was constructed and the electron microscope was used in order to observe the abrasion processes of die. By using the Nishihara's metal abrasion tester, the rotating abrasion was also tested to compare with the abrasion of die in wire drawing. In regard to these experiments thousands of electron photo-micrographs on the abrasion processes were taken and the other mechanical properties of the drawn wire were investigated.The following conclusions were obtained from the above experiments as to the mechanism of evolution of abrasion of die.1) The abrasion of the die is caused mainly by the particles of tungsten carbide leaving from die surface.2) This takes place at the time when a part of the wire adhering on die surface due to contact pressure leaves from the surface. The particles are taken off easily from the small part where is compressed repeatedly without the abrasion of the wire.By this study only a few points were solved as to the mechanism of evolution of abrasion of die. We hope this study will contribute to further studies on lubricant or die.