Abstract: A medical non-crosslinked pressure-sensitive adhesive composition which not only has relatively high resistance to water during perspiration or the like and shows a sufficient skin adhesive force, but also can contain a large amount of a liquid plasticizer and hence have reduced skin-irritating properties. These compositions comprise an adhesive polymer A having a weight-average molecular weight of 500,000-1,000,000, an adhesive polymer B having a weight-average molecular weight of 1,000,000-1,500,000, and a liquid plasticizer, wherein the adhesive polymer A is a polymer obtained by copolymerizing one or more alkyl (meth)acrylates with N-vinyl-2-pyrrolidone and the adhesive polymer B is either a polymer obtained by the polymerization of one or more alkyl (meth)acrylates or a polymer obtained by copolymerizing one or more alkyl (meth)acrylates with one or more comonomers other than N-vinyl-2-pyrrolidone.