PROBLEM TO BE SOLVED: To provide a novel methodology capable of easily bestowing, regardless of environments where a substrate is placed, an anticlouding and/or antifouling property onto the substrate surface and of maintaining the anticlouding and/or antifouling property of the substrate over a long period.SOLUTION: The surface hydrophilicity of a substrate having a hydrophilic surface is maintained over a long period by treating the hydrophilic surface of the substrate at least with an oxidant such as hydrogen peroxide, etc. Moreover, it is desirable to treat the hydrophilic surface with a base such as ammonia, etc.
