Abstract: The present invention relates to a melanin biosynthesis inhibitor containing terrein compound as an effective ingredient. The terrein compound can be easily separated from Penicillium sp KCTC 26245, a fungal strain inhabited in domestic soil. It does not directly inhibit tyrosinase but inhibits the expression of MITF (microphthalmia-associated transcription factor) by activating ERK (extracellular signal-regulated kinase) in melanin chromatocytes to give whitening effect. So, the melanin biosynthesis inhibiting effect of the compound is much greater than that of any other conventional inhibitors, and further the effect can be raised when the compound is used together with other inhibitors, owing to their different mechanisms. Thus, the compound of the present invention can be effectively used as a skin trouble treating agent, a skin whitening agent and a browning inhibitor.