The present invention provides a hydrophilic primer composition that can impart adhesiveness to a substrate when applied thereto and has good handling properties. This primer composition contains a polyester resin provided with a multivalent carboxylic residue and a glycol residue, and a modified polyolefin resin. The multivalent carboxylic residue contains a trivalent or higher multivalent carboxylic residue and/or a multivalent carboxylic residue provided with a metal sulfonate group. The value of the mass ratio of the polyester resin to the modified polyolefin resin is in the range of 8/2-2/8.