PURPOSE: To obtain a tyrosinase-inhibitor usable as a skin-beautifying agent for cosmetic and an agent for preventing blackening and browning of food, etc., by using 1,3,5-trihydroxybenzene derivative as an active component.

CONSTITUTION: The active component of the objective tyrosinase-inhibitor is the compound of formula I (R1 is H or glucose residue; R2 is H or group of formula II ; at least one of R1 groups is H but all of R1 and R2 groups are not H at the same time), e.g. phlorin of formula III, phloridzin of formula IV or phloretin of formula V. These compounds have remarkable tyrosinase- inhibiting activity comparable or superior to that of known agent such as kojic acid and arbutin. The amount of the compound is preferably about 0.5-1g per 100g of cosmetic in the case of using as a skin-beautifying cosmetic or 1-2g per 100l of solution in the case of using as a blackening preventing agent for food preferably in the form of an aqueous solution or an organic solvent solution.