To identify the effect of Tetraprenylacetone (TPA) which was one of newly developed stimulator of mucus production on gastric ulcer, TPA was medicated to 26 patients with benign gastric ulcer for 8 weeks. The results were as follows: 1) Of 26 patients with active and healing stage of gastric ulcer, 20 patients (77%) were cured. 2) Of not cured 6 patients, 2 patients were cured with 4 more weeks treatment of TPA. 3) side effect of TPA was not remarkable.