To investigate surface failure by scoring of gears, it is necessary to exactly evaluate the flash temperature rise generated on the meshing faces of the gears. In this report, the flash temperature rise caused by the moving heat source of which the distribution of heat intensity is assumed to be elliptical was calculated under the assumption of a three-dimensional heat flow. Further, the flash temperature rise caused by elliptically distributed heat source was compared to that caused by parabolically distributed heat source. From the calculated results it was found that the maximum value of the flash temperature rise caused by parabolically distributed heat source was about 1.07 times as large as that caused by elliptically distributed heat source.