A thin-film filter includes thin-film part having a film surface and a rear film surface arranged at the rear side of the film surface, a plurality of through holes, being formed to penetrate the thin-film part from the film surface to the rear film surface, the through holes are formed along by a slanting direction being made an acute angle or an obtuse angle with the film surface, and stripes-formed inner wall surfaces. The stripes-formed inner wall surfaces include stripe-like parts formed along by the slanting direction. The stripes-formed inner wall surfaces are formed inside the respective through holes.