A water-soluble or water-dispersible pressure-sensitive adhesive composition comprising a sulfonate-containing copolymer obtained from 20 to 99% by weight of an alkoxyethyl acrylate, 1 to 30% by weight of a styrenesulfonic acid salt, and up to 50% by weight of a monomer mixture of acrylic acid-caprolactone adducts. The composition exhibits excellent pressure-sensitive adhesion while showing satisfactory water solubility or dispersibility even in an acidic aqueous solution.