To obtain a medicine capable of treating or preventing prostatic cancer, by including a carboxamide derivative.

This medicine contains a compound of the formula (R1 and R2 are each H, OH or a lower alkoxy), its salt or its another derivative as an active ingredient. Preferably N-[1-methyl-1-(4-methoxyphenyl)ethyl]-3-oxo-4- aza-5α-androst-1-ene-17β-carboxamide is used as the compound of the formula. An oral administration in the form of tablet, capsule, granule, powder, syrup, etc., is preferable and a dose is 0.001-20 mg/kg weight per time and is administered once to several times daily. The compound of the formula shows inhibitory activity against tumor proliferation and excellent survival rate in comparison with finasteride sold in Europe and America as a therapeutic agent for benign prostatic hypertrophy.