Hemorrhagic gastric ulcer were often found in the population who suffered from the Great Hanshin-Awaji earthquake. Gastric biopsy samples taken from 136 patients in the population were examined for Helicobacter pylori by culture and PCR methods. Furthermore, production of CagA protein from isolates was investigated. Number of positive cases with culture and PCR method were 20 (50.0%) and 26 (65.0%) in hemorrhagic ulcer, 62 (86.1%) and 65 (90.3%) in other ulcers, respectively. Number of CagA positive strains from the patients of the hemorrhagic ulcer and other ulcers were 20 (76.9%) and 21 (32.3%), respectively. The significance in both ulcers was observed (p < 0.001). From the present results, it was considered that the stress of the earthquake, the infection of H. pylori and the production of CagA protein of the organism were combined and this caused hemorrhagic gastric ulcers.