A pattern formation method, comprising: a coating step, wherein a coating layer is formed by coating a substrate with the composition for forming an underlayer, comprising: a polymer having a repeating unit of formulae: -[-A 2 -L 2 -A 2' -]- wherein A 2 and A 2' are independently an aromatic group, or a saturated or unsaturated aliphatic hydrocarbon group, where said aromatic group or aliphatic hydrocarbon group is unsubstituted or substituted by a substituent selected from the group consisting of hydroxy group, alkyl group, aryl group, alkoxy group, nitro group, amide group, dialkylamino group, sulfonamide group, imide group, carboxy group, sulfonic acid ester group, alkylamino group and arylamino group, L 2 is of the following formulae: wherein Z 1 is selected from the group consisting of aliphatic group and aromatic group, said aliphatic group or aromatic group being selected from the group consisting of alkyl group, aryl group, alkoxy group, nitro group, amide group, dialkylamino group, sulfonamide group, imide group, carboxy group, sulfonic acid ester group, alkylamino group and arylamino group, and a solvent, a baking step, wherein an underlayer is formed by baking said coating layer in the existence of oxygen, a resist layer forming step, wherein a photoresist layer is formed on said underlayer, an exposure step, wherein said substrate coated with said underlayer and said photoresist layer is exposed, and a developing step, wherein the exposed substrate is developed with a developing solution. a polymer having a repeating unit of formulae: -[-A 2 -L 2 -A 2' -]- wherein A 2 and A 2' are independently an aromatic group, or a saturated or unsaturated aliphatic hydrocarbon group, where said aromatic group or aliphatic hydrocarbon group is unsubstituted or substituted by a substituent selected from the group consisting of hydroxy group, alkyl group, aryl group, alkoxy group, nitro group, amide group, dialkylamino group, sulfonamide group, imide group, carboxy group, sulfonic acid ester group, alkylamino group and arylamino group, L 2 is of the following formulae: wherein Z 1 is selected from the group consisting of aliphatic group and aromatic group, said aliphatic group or aromatic group being selected from the group consisting of alkyl group, aryl group, alkoxy group, nitro group, amide group, dialkylamino group, sulfonamide group, imide group, carboxy group, sulfonic acid ester group, alkylamino group and arylamino group, and a solvent, A 2 and A 2' are independently an aromatic group, or a saturated or unsaturated aliphatic hydrocarbon group, where said aromatic group or aliphatic hydrocarbon group is unsubstituted or substituted by a substituent selected from the group consisting of hydroxy group, alkyl group, aryl group, alkoxy group, nitro group, amide group, dialkylamino group, sulfonamide group, imide group, carboxy group, sulfonic acid ester group, alkylamino group and arylamino group, L 2 is of the following formulae: Z 1 is selected from the group consisting of aliphatic group and aromatic group, said aliphatic group or aromatic group being selected from the group consisting of alkyl group, aryl group, alkoxy group, nitro group, amide group, dialkylamino group, sulfonamide group, imide group, carboxy group, sulfonic acid ester group, alkylamino group and arylamino group, and a solvent, a baking step, wherein an underlayer is formed by baking said coating layer in the existence of oxygen, a resist layer forming step, wherein a photoresist layer is formed on said underlayer, an exposure step, wherein said substrate coated with said underlayer and said photoresist layer is exposed, and a developing step, wherein the exposed substrate is developed with a developing solution.