A manufacturing method of a thin film transistor, wherein a laminated body consisting of an intrinsic amorphous silicon layer and a conductive amorphous silicon layer is formed on a glass substrate, and annealed at low temperatures not higher than 600.degree. C. thereby obtaining a polycrystalline silicon film. The conductive amorphous silicon layer gives girth to a core for polycrystallization, and therefore the intrinsic amorphous silicon layer is easily recrystallized by annealing at low temperatures.