A pattern formation material capable of keeping dimensional accuracy of a pattern at a desired level even after a polymer is left standing for a long time after exposure and before baking, and a method of forming such a pattern formation material, which comprises a copolymer containing units containing a polycyclic aromatic ring, a condensed ring having at least one aromatic ring, or an aromatic ring having, as a substitution group, an alicyclic group, a branched alkyl or a halogen, and units from a monomer containing a photosensitive group, and a compound generating an acid by irradiation to ultraviolet rays.