ABSTRACT: Tyrosinase inhibitor-producing fungus of Trichoderma sp. strain H1-7, which was isolated from marine sediment, was investigated by phylogenetic analysis and physiological characteristics. Phylogenetic analyses of the strain were similar to Trichoderma atroviride or T. viride. Physiological characteristics of the strain were similar to T. viride, and based on these results, it was identified as T. viride. Characterization of tyrosinase inhibitory activity of a culture supernatant of the strain was investigated. The inhibitory activity of the supernatant of the strain decreased after cultivation for more than 3 days. Furthermore, sea water was not essential for the production of the tyrosinase inhibitor (TI). When TI production of the strain was compared to T. viride, the strain showed higher activity than T. viride. From this result, it seemed that the strain had characteristic features comparable to T. viride, which was isolated from the terrestrial environment. As TI production of the strain showed higher potential than that of T. viride, it is necessary to elucidate the chemical structure of TI exemplified in the present study.