A polymer comprising at least 1% by mole of a structural unit represented by Formula (2). In Formula (2), two R1s are the same or different from each other and are each a hydrogen atom or an alkyl group having 1 to 6 carbon atoms； X is a single bond, an oxygen atom, or a group represented by —；COO—；, —；OOC—；, —；CONH—；, —；NH—；, —；NHCO—；, —；NR3—；, or —；CH2O—；； Y is a single bond or an oligooxyalkylene group； two R2s are the same or different from each other and are each an alkyl group having 1 to 6 carbon atoms； R3 is an alkyl group having 1 to 6 carbon atoms； m is an integer of 1 to 10； and n is an integer of 2 to 10) and having a number average molecular weight of 5,000 or more has various characteristics suitable for use in contact with a living organism and can be easily produced.
