By adding a compound represented by the following general formulas: ##STR1## to a conventional photoresist composition comprising a cyclized product of conjugated diene homopolymer or copolymer and a photo-crosslinking agent soluble in an organic solvent, an image having a high degree of resolution can be obtained even when a base board having a surface of a high reflectance is used, with a high reproducibility and without being affected by prebaking conditions.