The invention provides a pigment composition having a pigment and a dispersant, wherein the dispersant is a copolymer comprising: a repeating unit (a) having a specific structure; and a repeating unit (b) having an ionic group. The invention ether provides a water-based pigment dispersion containing: the pigment composition; and water or a water-based carrier medium containing water and an organic solvent. The invention further provides a method for producing the water-based pigment dispersion. The invention further provides a water-based ink for ink jet recording containing the water-based pigment dispersion. The invention further provides a polymer compound having, as copolymerization components, a monomer having a specific structure, (meth)acrylic acid, and benzyl (meth)acrylate.