To provide a coating composition and its production method, in which adhesion to a polyolefin is excellent, and further compatibility with a polar coating resin and solution stability are excellent.

The method for producing a coating composition for a polyolefin resin comprises graft-polymerization of polypropylene glycol (meth)acrylate to a chlorinated polyolefin and graft-copolymerization of a (meth)acrylic acid monomer thereto, wherein a chlorine content of the chlorinated polyolefin is 16-35 wt.%, a mass ratio of the (meth)acrylic acid monomer to the chlorinated polyolefin is 50:50 to 97;3, and the (meth)acrylic acid monomer contains 5-30 wt.% of polypropylene glycol (meth)acrylate.