<p>Wear on tooth surface of gears occurs while gear pair transmits a power and a rotation. The progression of the wear gradually degrade the performance for the change in the tooth profile. Especially, the edge contact provides a large wear to the tooth surface. A tooth profile modification is widely used to prevent the edge contact. However, there is few researches about the effect of tooth profile modification to the surface wear. In this study, we investigated the effect of tooth profile modification on the tooth wear of involute spur gear in the cyclic wear test with two types of gears. Furthermore, we developed a computer program to predict the amount of the wear on the tooth surface considering the edge contact for the spur gear. The method is based on two types of wear equations. One is Soda's theory under lubricated condition, and the other is derived from the ploughing wear model. We compered the calculated result with experimental data, and discussed the effect of the tooth profile modification on the tooth wear.</p>