A device for interstitial fluid extraction, having a base material formed from a synthetic resin film, a pressure sensitive adhesive layer, a hydrogel layer formed from at least one hydrophilic polymer selected from the group consisting of polyvinyl alcohol and polyvinyl pyrrolidone, and a release layer, wherein the hydrogel layer has an area of a size that the pressure sensitive adhesive layer is exposed from around the hydrogel layer, does substantially not contain a sodium ion and causes no water separation.
