Melanin is a key factor determining the color of skin. The enzyme tyrosinase plays the most important role in melanin synthesis (melanogenesis) (1,2). Several tyrosinase inhibitors (chemicals, plant extracts, animal products) have been proposed, based on the view that melanogenesis can be controlled, and skin-whitening products can be developed if tyrosinase activity can be suppressed. However, few have been put to practical use. In practice, it is difficult to develop these candidate materials from in vitro studies to approve for human use, even if inhibitory effects on mushroom-derived tyrosinase or pigment cells can be identified. In addition to showing adequate efficacy and safety, there are many problems to consider, such as stability of the products, production and marketing costs, and perception of the user.