PURPOSE: To obtain anticancer drug having strong differentiationinducing action against various cancers containing vitamin D derivative and butyric acid or salt of said acid as active ingredients.

CONSTITUTION: 1 pt.wt. butyric acid is mixed with 10-6-10-1 pt.wt., preferably 5×10-5-10-2 pt.wt. vitamin D derivative and conventional drug carrier or excipient, etc., is suitably added, then made to formulation by usual method to afford the aimed drug. The drug is able to be formed in a shape of solid formulation such as powder, granule, tablet, sphere or capsule, or liquid formulation such as elixir, suspension, emulsion, syrup, alcoholic solution or oily solution. Administration dose is 0.003-10000μg, preferably 0.3-5000μg for 1 day of adult. As the vitamin D derivative, 1α, 25-dihydroxycholecalciferol, etc., is exemplified.