Planetary gear sets are widely used in hybrid or electric vehicles. Although they have many advantages, they have been known to develop noise and vibration problems. There have been many reports dealing with the problems' characteristics for two-axis driving, but very few for three-axis driving. This paper reports three-axis driving performed on a developed driving stand, with driving torque measured by a high response torque sensor on each driving axis. Under these conditions it was found that the meshing frequency occurred at two kinds of frequency harmonics.