A release agent composition, which includes a fluorocopolymer having structural units based on a monomer (a) having a C1-6 polyfluoroalkyl group and structural units based on monomer (b) having a C18-30 alkyl group, and a medium, where the mass ratio of the structural units based on the monomer (a) to the structural units based on the monomer (b) (the structural units based on the monomer (a)/the structural units based on the monomer (b)) is from 1/1 to 1/10.