Oriented SrTiO3 thin films were grown in situ on p-type Si(100) substrates by radio frequency magnetron sputtering. The orientations of the films were varied by controlling both growth temperature and oxygen-to-argon content ratio in a discharge gas. Deposition at 640-degrees-C in 100% argon discharge yielded (111)-oriented SrTiO3 film. Film with (100) orientation was obtained by addition of oxygen as a discharge gas at lower growth temperature (< 620-degrees-C). SrTiO3 thin films were composed of three regions, an external surface layer, a main layer and an interface layer. The films had very sharp interface layers. The films had a fairly dense structure with homogeneous grain and a columnar structure was observed in the cross section morphology.