An object of the present invention is to provide a polymer film that can be adjusted to movement or a fine uneven surface of a living body and has excellent ability to adhere to a biological tissue. The present invention provides a polymer film, comprising a block copolymer having a structure in which branched polyalkylene glycol and polyhydroxyalkanoic acid are bound to each other, wherein the polymer film has a film thickness of 10 to 1000 nm. The branched polyalkylene glycol has at least three terminal hydroxyl groups per molecule, the mass percentage of the branched polyalkylene glycol relative to the total mass of the block copolymer is 1% to 30%, and a value obtained by dividing the average molecular weight of polyhydroxyalkanoic acid in the block copolymer by X that is the number of terminal hydroxyl groups present per a single molecule of the branched polyalkylene glycol is 10000 to 30000.
