PURPOSE: To provide a tackifier resin useful for the production of water-based adhesive compositions excellent in adhesion and heat resistance and stable against high mechanical shear forces caused by gear pumps, roll coaters, etc., by emulsifying a tackifier resin in the presence of an emulsifier, etc.

CONSTITUTION: (A) 100 pts.wt. of one kind or more of tackifier resins selected from a rosin (derivative), a petroleum resin, and a terpene resin, (B) an emulsifier such as a sulfonated α-olefin preferably in an amount of 1-5 pts.wt., and (C) one kind or more of protective colloids selected from a water-soluble casein salt, gelatin, polyacrylic acid, PVA (derivative), cellulose (derivative) preferably in an amount of 1-5 pts.wt., are compounded with each other and emulsified to provide the objective tackifier resin emulsion. The emulsion is compounded with an acrylic polymer emulsion and/or a latex for adhesives to provide a water-based adhesive composition.