Additive manufacturing is an innovative manufacturing technology for realizing complex structural parts. In particular, the selective laser melting (SLM) can produce highly precise parts with high dimensional accuracy. We are working to improve gas turbine efficiency by applying the SLM to hot parts of our industrial gas turbine. Ni-base casting alloys are applied to the important hot parts of the gas turbine, but the Ni-base superalloys fabricated by SLM has various difficulties, especially for high temperature strength. In the SLM process, solidification progresses extremely fast, so very fine crystal grains are formed. In addition, due to the large temperature gradient and the high solidification rate, very fine columnar crystal grains are formed with strong anisotropy. In this research, the effect of microstructural features, such as grain shape and distribution of precipitates, on high temperature strength and ductility was investigated for Ni-base alloys similar to IN 939.