We treated a patient who had gastrointestinal perforation during chemotherapy with docetaxel and S-1 which was successfully treated with percutaneous drainage. A 66-year-old man was admitted to our hospital with complaints of abdominal pain. Gastric cancer (T3N1M0) had been diagnosed 3 years earlier, and distal gastrectomy had been performed. Two years later, intrapelvic recurrence of the cancer was diagnosed. We administered docetaxel and S-1. After 3 courses of chemotherapy, he complained of abdominal pain of sudden onset. Computed tomography showed free air and limited ascites, and gastrointestinal perforation was diagnosed. We performed percutaneous drainage. The abdominal pain improved 3 days later, and he was able to eat meals 15 days after the onset of abdominal pain. He was discharged 27 days after admission. Because the patient's general condition was poor, we started providing best supportive care only. He died 10 months after the perforation was found.