PURPOSE: To reduce the cost of a pressure sensor by forming an SiO2 film in the boundary between an oxide single crystal thin film formed on an Si substrate and the Si substrate, growing an Si single crystal thin film on the oxide single crystal thin film, forming a resistance region on the Si single crytal thin film, and removing the part of the Si substrate which includes the range corresponding to the resistance region, thereby reducing the irregularity in the characteristics.

CONSTITUTION: After an oxide single crystal thin film is epitaxially grown on an Si substrate, an SiO2 layer is formed in the boundary between the oxide single crystal thin film and the Si substrate. An Si single crystal thin film is epitaxially grown on the oxide single crystal thin film. A resistance region 25 is formed by ion implanting on the Si single crystal thin film 24. Etching protective films 26 are formed on both side surfaces of the substrate so that the etching protective film of the silicon substrate side of the part to be formed with a diaphragm is removed, and the silicon substrate part is etched. The film 26, an SiO2 layer 23, and the oxide single crystal thin film 22 are removed to obtain an Si diaphragm. Subsequently, an insulating film 27 and electrodes 28 are formed by a normal method.