This paper aims to report the effect of transverse magnetic fields on melt convection and oxygen transfers in silicon melt during single-crystal growth. Three-dimensional and time-dependent calculation was carried out to clarify distributions of velocity, temperature and oxygen in the melt. Asymmetric temperature and oxygen distributions were obtained from the calculation, which were due to unidirectional magnetic fields. Oxygen distribution in the melt was also discussed to clarify how surface-tension-driven flow affect the oxygen distribution at an interface between crystals and melt.