In this study, we investigated the anticancer activity of the fin of Thunnus Thynnus (TT). TT was extracted with methanol (TTM), and then further fractionated into four subfractions by using solvent partition method, affording hexane (TTMH), methanol (TTMM), butanol (TTMB) and aquous (TTMA) soluble fractions. We determined the cytotoxicity of these four fractions in four kind of cancer cell lines, such as HepG2, MCF-7, B16-F10 and HT29 by MTT assay. The TTMM showed the strongest cytotoxic effect at the concentration of 150 ${mu}g/mL$, displaying 95% on the HepG2 cell lines and 82% on MCF-7 cell line. The morphological changes such as membrane shirinking and blebbing of cells were also observed by TTMM treatment in HT29 cell. In addition, we observed that quinone reductase (QR) activity was elevated by only TTMM and TTMH treatments in HepG2 cell. QR activity was increased to around 2.0 and 1.8 times in TTMM and TTMH treated HepG2 cell at 100 ${mu}g/mL$, respectively, compared to that in control. Although further studies are needed, the present work could suggest that the fin of TT has a potential to be usable as a chemopreventive agent against cancer.