A nanocomposite comprises a nanostructure, and a copolymer adsorbed to the nanostructure and containing at least one ionic monomer unit and a different monomer unit from the ionic monomer unit; the ionic monomer unit selected from the group consisting of a zwitterionic monomer unit and a cationic monomer unit which are represented by the following formula (1): (in the formula (1), R1, R2, and R3 each independently represent any one of a hydrogen atom and a monovalent organic group having 1 to 20 carbon atoms, Y1 represents any one of a carbonyl group and an arylene group, Y2 represents any one of —O— and —NH—, n is 0 or 1, R4 represents a divalent organic group having 1 to 20 carbon atoms, and X represents any one of a zwitterionic group and a cationic group).