Slipperiness-imparting agent and slipperiness-imparting method

[Problem] To provide a slipperiness-imparting agent capable of imparting durable slipperiness (in particular, slipperiness when wet). [Solution] The present invention was completed upon the discovery that a slipperiness-imparting agent can impart durable slipperiness to a base material surface by using a simple method called light irradiation, said slipperiness-imparting agent containing: a copolymer containing a structural unit (A) based on 2-methacryloyloxyethyl phosphorylcholine and a structural unit (B) based on a photoreactive functional group-containing monomer; or a copolymer containing a structural unit based on a structural unit (A) based on 2-methacryloyloxyethyl phosphorylcholine, a photoreactive functional group-containing monomer (B), and a hydrophobic group-containing monomer (C).