Washing solution, washing tool, and washing kit

A washing solution which can be used for washing recessed portions formed on one surface of a light-permeable antireflective structure, wherein the light-permeable antireflective structure has, on the one surface thereof, multiple protruded portions formed at intervals each of which is equal to or shorter than the wavelength of a visible light region, the light-permeable antireflective structure is so adapted as to prevent the reflection of light entering the one surface on the one surface, and each of the recessed portions is a region formed between any adjacent two of the protruded portions. The washing solution has a pH value of 10.00 or more.