Introduction: Ulcers may occur in the entire gastrointestinal tract, mostly in gastric and duodenal. In general, patients usually complain of gastric ulcer dyspepsia (collection of symptoms such as nausea, vomiting, bloating, heartburn, belching, feeling of fullness in the gut, burning, and quickly feel full). WHO recommends the use of traditional medicines, including herbal in the maintenance of public health. Kencur is one herb that is often used in the treatment of gastric inflammation.Objectives: This research is to determine the effects of Kencur’s rhizome extract in preventing gastric ulcer by observing the depth of gastric mucosal erosion mice.Methods: The research method used is true experimental design in laboratorium with complete randomized design, which is comparative. Experimental animals used were Swiss Webster male mice, divided into 6 groups (n = 5). Group I,II, and III were given kencur’s rhizome extract with dose 0,52; 1,04; and 1,3 mg/kg of mice. Group IV was given CMC 1 %, group V was given asetosal, and group VI was given omeprazole. The data observed are the depth of gastric mucosa erosion, evaluated by a scoring system. The data is analyzed by using the Kruskal Wallis followed by Mann-Whitney test. Results: The result shows a very significant differences between groups I, II, III compared to group IV. There is very significant differences between groups I, III and group V. The comparison between group II and group V shows a significant result, while the comparison between group I, II, III and group VI shows no significant result.Conclusion:Kencur’s rhizome extract prevent gastric mucosa erosion of mice (gastric ulcer) that is induced by asetosal.