A method of forming a semiconductor thin film includes: a step of forming an amorphous semiconductor thin film over a transparent substrate; a step of forming a crystalline semiconductor thin film by irradiating the amorphous semiconductor thin film with laser light to provide heat treatment and thereby crystallizing the amorphous semiconductor thin film; and an inspection step of inspecting the crystalline semiconductor thin film. The inspection step includes a step of obtaining a transmission image of the crystalline semiconductor thin film by irradiating the crystalline semiconductor thin film with light from a rear side of the transparent substrate and taking an image, and a screening step of performing screening of the crystalline semiconductor thin film based on the obtained transmission image.