Provided are: a tyrosinase inhibitor having an excellent tyrosinase-inhibiting activity and high safety； and a method for producing a tyrosinase inhibitor. A method for producing a tyrosinase inhibitor, characterized by comprising the steps of: bringing a hydroxycarboxylic acid powder into contact with living earthworm, diluting the resultant mixture with water to adjust the pH value of the resultant solution to 2 to 5 and then holding the pH-adjusted solution for 3 to 180 minutes, or alternatively, bringing an aqueous hydroxycarboxylic acid solution having a pH value of 2 to 5 into contact with living earthworm and then holding the resultant solution for 3 to 180 minutes； washing the living earthworm with water； pulverizing the washed earthworm； and lyophilizing the pulverized product.提供具有優異酪胺酸酶抑制作用、具備高安全性之酪胺酸酶抑制劑及酪胺酸酶抑制劑之製造方法。一種酪胺酸酶抑制劑之製造方法，其特徵係具備使粉末狀羥基羧酸與生的蚯蚓相接觸，以水稀釋並調整pH值為2~5，保持3~180分鐘之後，或，於pH值2~5之羥基羧酸水溶液與生的蚯蚓相接觸，保持3~180分鐘之後，以水清洗生的蚯蚓並將之磨碎，凍結乾燥所得到之磨碎物之步驟。
