An object of the present invention is to provide a material which can be safely ingested and which inhibits skin pigmentation. Therefore, the invention is a skin pigmentation inhibitor, containing a β-nicotinamide mononucleotide or a pharmaceutically acceptable salt thereof； and a solvate thereof as an active ingredient； a health supplement which contains the skin pigmentation inhibitor and is ingested to inhibit skin pigmentation； and a method for inhibiting skin pigmentation, including ingesting the skin pigmentation inhibitor.
