Because the life of power transmission gears has come to be greatly affected by the tooth surface strength, it is an important problem to clarify the influence of tooth profile and helix deviation on the tooth surface strength of carburized helical gears in a practical design. In this research, first, the experiments were carried out to measure the tooth surface strength using the test gears with six kinds of different tooth surface deviation. Next, this experimental result was arranged as S-N diagram by using Hertzian contact stress calculated in consideration of the tooth surface deviation. The influence of the tooth surface deviation on the tooth surface fatigue life was quantitatively shown by the empirical formula. Using the obtained result, the influence which the kind and the amount of the tooth profile and helix deviation exerted on the tooth surface fatigue life was considered. In addition, the effect of crowning was discussed.