A composition includes a polymer and a solvent. The polymer includes a group (X) which is at least one selected from the group consisting of: a group including at least two cyano groups; a group including —B(OR)2; a group including —PO(OR)2; and a group including —P(OR)2. Each R independently represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. The polymer preferably includes the group (X) at an end of a main chain thereof or at an end of a side chain thereof.