Provided is a surface conditioner which can control the surface free energy of a coating agent by being added in a small amount to the coating agent, can improve interlayer adhesion in a laminated coating film by increasing not only wettability to a substrate or an underlying coating film but also wettability to a cured coating film thereof, and also does not cause foaming during baking coating in a baking process. This surface conditioner contains a copolymer composed of: a siloxy group-containing acrylate monomer represented by formula (I) and/or a fluorine-containing (meth)acrylate monomer represented by CH2═C(R4)-CO-O-R5-RF; and a (meth)acrylamide monomer represented by CH2═C(R6)-CO-O-R7-R8 and/or an unsaturated group-containing morpholine amide monomer, the surface conditioner having a weight average molecular weight of 1500-50000.