Disclosed is a primer composition for coating having excellent adhesion properties to a substrate and comprising a polyolefin resin or acrylic resin, without the use of a chlorine-containing compound, which primer composition essentially comprises a polymer (A) having at least a unit of a (meth)acrylic ester monomer (a) in which acryloyloxy group or methacryloyloxy group is bonded to secondary carbon atom or tertiary carbon atom.