Provided is a lubricity-imparting agent that can impart durable lubricity (in particular, lubricity at the time of wetting) to a substrate. It has been found that a lubricity-imparting agent including a copolymer containing a constitutional unit (A) based on 2-methacryloyloxyethyl phosphorylcholine and a constitutional unit (B) based on a photoreactive functional group-containing monomer, or a copolymer containing a constitutional unit (A) based on 2-methacryloyloxyethyl phosphorylcholine, a constitutional unit (B) based on a photoreactive functional group-containing monomer, and a constitutional unit (C) based on a hydrophobic group-containing monomer can impart durable lubricity to a substrate surface through a simple approach called photoirradiation.
