The present invention has its object to provide a pressure sensitive adhesive composition which can be applied using no organic solvent or using almost no organic solvent and which manifests excellent pressure sensitive adhesion characteristics. This object can be achieved by a pressure sensitive adhesive composition which comprises, as essential constituents, the following: (A) an oxyalkylene polymer containing 0.3 to 0.7 equivalent of a hydrolyzable silyl group in each molecule and having a number average molecular weight of 15,000 to 100,000 (hydrolyzable silyl group-containing polymer); (B) a tackifier resin; (C) a curing catalyst.