A soft film, a sponge, or a sheet in the dried state is provided, which is capable of forming a hydrogel absorbing water or blood. The film is obtainable by preparing a film-state material in the dried state from either a solution of poly(acrylic acid) or a solution of polyvinylpyrrolidone, and bringing the film-state material into contact with the other remaining solution, and then drying or freeze-drying it.