Bioactive components derive from natural substances have been widely studied for the use as an anticancer drug. A study on a bioactive component from matah merah mollusks (Cerithidea obtusa) as an anticancer has not yet been reported. This research was intended to find the best method of extraction for the bioactive components of this animal. The research were divided into of two stages: (1) an extraction of matah merah mollusks by applying various solvents (water, water and methanol, acetone, ethyl acetate, and methanol), and (2) anti-proliferation ability of matah merah mollusks against tumor cell line (HeLa/cervix cancer, A 549, and K562). The results showed that the best extraction time was is 72 hours with the ratio of main material and solvents being 1:6 (w/v). The result also found that acetone of 25 ppm was the best solution resulted the strongest inhibiting power against cancer cells (90.62% against HeLa/cervix cancer, 79.84% against lung cancer/A 549, and 76.71% against leukemia/ K562.