The bulk temperature rise was studied when a moving heat source with variational heat quantity was applied repeatedly at regular intervals to the surface of an isotropic and homogeneous rectangular shaped body used as a model of a spur gear tooth. The effect of radiation at the inner surface of a boss on the bulk temperature rise is reduced as the distance between the inner surface of the boss and the working tooth flank is increased. The bulk temperature rise is almost inversely proportional to the heat supply interval. The size of the heat supply region and the moving direction of the heat source scarcely affect the bulk temperature rise. in a |νν^^-| range of not less than 1000, the bulk temperature rise is not affected by the moving velocity of the heat source, and the approximate bulk temperature rise can be obtained by dividing the temperature rise of the working tooth flank due to a stationary heat source by the number of teeth.