PURPOSE: To efficiently obtain potato tuber in a short time regardless of soil, climate, etc., by culturing a sterile plant material of potato prepared by tissue culture in a specific medium.

CONSTITUTION: A plant material such as tuber or shoot apex of potato subjected to surface serialization is laid on a solid or liquid medium (pH 4.0-7.0) for tissue culture containing 0.01-10mg/l plant growth regulator such as ancymidol, paclobutarazol or uniconazole in the ratio of one material based on 1-100ml medium and cultured under irradiation of 100-100,000lux light at 10-30°C (preferably 21-25°C) for 1-20 weeks to give a sterile culture plant material. Then the plant material is cut, divided, laid on a liquid medium containing plant growth regulator (preferably 0.01-10mg/l paclobutrazol or uniconazole) in the ratio of one cut fragment based on 1-100ml liquid medium and subjected to static culture or shaking culture at 10-30°C for 1-2 weeks to give the aimed tuber.