A main object of the present invention is to provide a polymer precursor which exhibits high transmittance to a shorter wavelength range with respect to an electromagnetic wave though the polymer precursor has a part which sequences an unsaturated bond having a π electron orbit and a single bond alternately. In order to attain the object, a polymer precursor comprising a part which sequences an unsaturated bond having a π electron orbit and a single bond alternately, wherein the polymer precursor has a first functional group and a second functional group which form a repeating unit constituting a polymer skeleton of an end product by an intramolecular reaction, wherein at least a part of a conjugated state formed by the π electron orbit in the molecule is disconnected or weakened due to a three-dimensional structure of the molecule, and wherein a transmittance with respect to an electromagnetic wave of at least one wavelength selected from the group consisting of 436 nm, 405 nm, 365 nm, 248 nm and 193 nm is improved, is provided.