The present invention improves a method of forming a surface unevenness using a difference in etching rates, and relaxes limitations on substrates in this method. In a method of the present invention, an uneven surface is formed by a method including applying pressure to a predetermined region in a surface of a thin film formed on a substrate, and etching a region including at least a portion of the predetermined region and at least a portion of the reminder of the surface that excludes the predetermined region. An etching rate difference within the thin film increases freedom in selecting a substrate material.