A method for producing an optical element includes: forming a resist layer on a main surface of a substrate; forming a pattern region in the resist layer; forming a groove; forming a dielectric layer covering the pattern region; and forming an optical functional portion. The pattern region is formed in the resist layer. The groove is formed in a portion corresponding to a periphery of the pattern region as viewed in a direction orthogonal to the main surface. A dielectric is deposited to form the dielectric layer. After the dielectric layer covering the pattern region is formed, the resist layer is removed to form the optical functional portion at a position where the pattern region is disposed on the main surface. The optical functional portion is made of the dielectric.