A method of evaluating crystallinity includes irradiating light from below a polycrystalline silicon substrate, allowing the irradiated light to pass through the polycrystalline silicon substrate and a circular polarizing plate disposed above the polycrystalline silicon substrate, measuring an intensity of light having passed through the circular polarizing plate at a location vertically above the circular polarizing plate, notifying that there is an error in a crystallinity of the polycrystalline silicon substrate when the measured intensity of the light is out of an error margin of a predetermined criterion intensity of light.