Sputtering device and transistor

Provided are a novel metal oxide and a novel transistor. A metal oxide film is formed by using a sputtering device characterized by comprising a first sputtering target, a second sputtering target, a shutter, and a substrate holder, the first sputtering target comprising a conductive material, the second sputtering target comprising an insulating material, the shutter being positioned between the substrate holder and the first sputtering target and second sputtering target, the shutter being provided with a cut-out part, and the substrate holder facing the first sputtering target or the second sputtering target via the cut-out in the shutter. In the transistor, said metal oxide film is used as a channel formation region.