PURPOSE: An aqueous coating compostion having remarkably improved adhesivity to the surface of a substrate, obtained by blending an emulsion synthetic resin with a specific cyclopentadiene tackifier resin.

CONSTITUTION: A) 100 parts by wt. of an emulsion synthetic resin, e.g., acrylic resin, vinyl acetate resin, styrene-butadiene resin, etc., is blended with B) 5W100 parts by wt. of a cyclopentadiene tackifier resin obtained by polymerizing a monomer of cyclopentadiene compound with an ester bond-containing monoolefin monomer in the absebce of a nonradical catalyst in an inert hydrocarbon solvent or without the solvent at 200W300°C for 0.5W20 hours under heating, having a saponification value of 100-200 and a softening point of 70-140°C.