PURPOSE: To readily form a polycrystalline thin film which is electrically insulated and separated and which has a crystal particle size of a large crystal size on the flat surface, while heat stress is suppressed.

CONSTITUTION: This embodiment has a step of forming a material 111 that has one or two or more recesses and that becomes a stopper at removing selectively a crystal growing upwardly, a step of growing a crystal on the material 111, a step of removing a crystal grown excluding the upper part of the recess, a step of heat-treating a crystal above the recess at the melting point or less to form a polycrystal 113 having a crystal particle size identical to or larger than a film thickness of a crystal by particle-growing, and a step of using the upper surface of the material 111 as a stopper and removing a polycrystal formed exceeding the upper surface of the material 111.