PROBLEM TO BE SOLVED: To provide a thin film capable of adhering to a living body or a biomaterial with sufficient strength and without using self-adhesive component, and hardly peeled off even when adhered to an uneven surface in motion.SOLUTION: A production method of a hydrogel thin film comprises a foam film-forming step of forming a foam film of an aqueous solution containing a surface-active compound having two or more polymerizable functional groups in one molecule, or a foam film of an aqueous solution containing a compound having two or more polymerizable functional groups in one molecule and a surfactant, to an opening of a frame and a gelling step of reacting the functional groups to bond and crosslinking between the molecules of the surface active compounds or the compounds thereby forming a hydrogel thin film gelled of the foam film in a state including water.
