The effect of Ba deoxidation on the oxygen content and non-metallic inclusions in NiTi alloys was investigated. The NiTi alloy melt was held in a CaO crucible at 1673 K under Ar gas flow for 0-600 s. Metallic Ba (0.5-1.5 mass% with respect to NiTi alloy melt) was added to the melt. After melting, oxygen content of 710 and 330 mass ppm decreased to 210 and 130 mass ppm, respectively, after a holding time of 300 s after the addition of Ba. The oxygen in the melts was reduced to as low as 64 mass ppm after a second Ba deoxidation. The non-metallic inclusions observed in the NiTi alloys were the Ti4Ni2O (X) and Ti(C,N,O) (X) types. Decreased oxygen content through Ba deoxidation caused a change in the main phase of the non-metallic inclusions from the Ti4Ni2O (X) type to the Ti(C,N,O) (X) type, and a decrease in the area percents of the non-metallic inclusions.