A molded product having a phase separation structure formed by photopolymerization of a photopomerizable composition and imparting a sharp diffraction spot at a high diffraction efficiency, and a method for manufacturing same are provided. The molded product (1) comprises a matrix (2) and a multiple columnar structures (3) disposed within the matrix (2) and having an index of refraction different from the matrix (2), wherein the half width of a diffraction spot is 0.6° or less and diffraction efficiency is 10% or greater in an angular spectrum obtained by irradiation with a laser beam having an intensity distribution of standard normal distribution and a half width of the intensity distribution of 0.5°. The multiple columnar structures (3) are oriented in approximately the same direction, and are aligned in a regular lattice on a plane perpendicular to said orientation direction.