A synthetic polymer film whose surface has a plurality of raised or recessed portions, wherein a two-dimensional size of the plurality of raised or recessed portions is in a range of not less than 0.5 μm and not more than 3 μm when viewed in a normal direction of the synthetic polymer film, the synthetic polymer film has a crosslink structure and contains an organic carboxylic acid, at the lapse of 5 minutes since placing a 200 μL drop of water on the surface of the synthetic polymer film, a pH of an aqueous solution is less than 4, and an area equivalent circle diameter of the aqueous solution is not less than 20 mm, and at the lapse of 60 seconds since placing a drop of water on the surface of the synthetic polymer film, a static contact angle of the water drop with respect to the surface is less than 3°.