PROBLEM TO BE SOLVED: To provide a new compound excellent in whitening effect, a whitening agent, and a production method thereof.SOLUTION: The present invention provides a compound which is 4-((2,4,8a)-2,4-dihydroxy-2,5,5,8a-tetramethyldecahydronaphthalen-1-yl)but-3-en-2-one or medically acceptable salt thereof. A whitening agent comprises the compound or the medically acceptable salt thereof as an active ingredient. A production method of the compound comprises the steps of: fermenting a stevia plant or an extract from the stevia plant by bacteria producing lactic acid to prepare a fermentation object of stevia by the bacteria producing lactic acid and collecting the compound from the fermentation object of stevia by the bacteria producing lactic acid.
