Chemoradiation was performed at Osaka Police Hospital's department of respiratory medicine on a 70-year-old male with small cell lung carcinoma(cT4N3M0, cStage ⅢC). Subsequent to secondary chemotherapy for multiple bone metastases that had been observed, he received care to control the disease. He arrived at the hospital complaining of epigastric pain. He got CT-scan and was referred to our department because of a suspected hematoma around the right gastroepiploic artery. He was treated conservatively because circulatory dynamics were steady and there was no indication that anemia had progressed. However, when a test laparotomy was performed the day after the start of treatment because he presented with decreased blood pressure and progressive anemia, a massive hematoma was found around the right gastroepiploic artery. The hematoma was removed, and hemostasis was performed. Based on the pathological findings of the excised specimen, he was diagnosed with abdominal metastasis of small cell lung carcinoma. This is a report on our experience and a literature review on a case of mesenteric hematoma caused by abdominal metastasis of small cell lung carcinoma.