The present invention provides a polymer compound that can be expected to inhibit activation of a coagulation system, a complement system or a platelet system when brought into contact with in vivo tissue and/or blood since the compound is capable of containing intermediate water, and a composition and a device using the same. This problem is solved by a polymer compound containing a repeating unit represented by general formula (A), and used in contact with in vivo tissue and/or blood, in which in a process in which the polymer compound caused to contain water in a prescribed water content is cooled to −100° C. and thereafter heated at a temperature rise rate of 5.0° C./min, a temperature region where exothermicity occurs is present in the range of −80° C. or more and −25° C. or less, and a temperature region where endothermicity occurs is present in the range of −25° C. or more and lower than 0° C.:wherein R represents a hydrocarbon group having 1 to 20 carbon atoms.
