A photoresist composition capable of forming a high resolution pattern without an additional heating process includes an alkali-soluble phenol polymer in an amount of 10 to 70 parts by weight, including at least one unit of Formula 1, a photo-acid generator in an amount of 0.5 to 10 parts by weight, a dissolution inhibitor in an amount of 5 to 50 parts by weight, including at least one unit of Formula 2, and a solvent in an amount of 10 to 90 parts by weight, wherein the amounts of the foregoing components is based on a total of 100 parts by weight of alkali-soluble phenol polymer, photo-acid generator, dissolution inhibitor, and solvent, and wherein Formulas 1 and 2 have the structures: wherein R is a methyl group, wherein R1, R2 and R3 are the same or different and are hydrogen or t-butyl vinyl ether protective groups.