An object is to provide a material suitably used for a semiconductor included in a transistor, a diode, or the like. Another object is to provide a semiconductor device including a transistor in which the condition of an electron state at an interface between an oxide semiconductor film and a gate insulating film in contact with the oxide semiconductor film is favorable. Further, another object is to manufacture a highly reliable semiconductor device by giving stable electric characteristics to a transistor in which an oxide semiconductor film is used for a channel. A semiconductor device is formed using an oxide material which includes crystal with c-axis alignment, which has a triangular or hexagonal atomic arrangement when seen from the direction of a surface or an interface and rotates around the c-axis.