PURPOSE: To obtain a cell proliferation inhibitor, containing a transforming growth factor β(TGF-β) as an active ingredient, capable of exhibiting powerful cell proliferation inhibitory action on hepatic cancer cells and useful for preventing and treating hepatic cancer.

CONSTITUTION: A cell proliferation inhibitor containing TGF-β capable of performing various actions of cell proliferation, differentiation, function, etc., such as inhibition of the final differentiation of profat cells, in vitro promotion of wound treatment, promotion of bone resporption or stimulation of collagen synthesis, as an active ingredient. The TGF-β is capable of remarkably inhibiting proliferation of human hepatic cancer derived both from embryoma and from cell hepatic cancer and the dose therefore is within the range of 0.01-10μg, preferably 0.1-1μg per kg body weight a day.