We observed fluctuation of the three-phase (solid, melt and ambient atmosphere) boundary position in silicon liquid bridges. We proved by measuring interface fluctuation and temperature fluctuation simultaneously that this interface fluctuation is caused by the formation and fluctuation of asymmetrical temperature field due to Marangoni Row instability. The amplitude of interface fluctuation decreased with increasing oxygen partial pressure. This decrease in interface fluctuation suggests that oxygen partial pressure is a factor that influences Marangoni flow in molten silicon.