The patient is male in his 60's. He underwent endoscopic examination for anemia, which was found during screening of high PSA value. Endoscopic examination revealed a gastric cancer and 3 colorectal cancers. Histological results from biopsy was HER2 positive poorly differentiated adenocarcinoma in gastric tumor and moderately differentiated adenocarcinoma in colorectal tumor. Chest CT showed a pulmonary nodule in the middle right lung. Histological diagnosis was TTF-1 positive adenocarcinoma, meaning primary lung cancer. Histological examination of prostate biopsy also showed adenocarcinoma. Clinical stages were Stage III B of gastric cancer, Stage III a of colorectal cancer, Stage I A of lung cancer and Stage I of prostate cancer. Neoadjuvant chemotherapy for gastric cancer was performed because gastric cancer with advanced clinical stage was regard as a prognostic factor. Neoadjuvant chemotherapy shrinked gastric and colorectal cancers, so we performed distal gastrectomy for gastric cancer and super low anterior resection for colorectal cancer. Patient was discharged 22 days after operation without any serious adverse events. Hormonal treatment for prostate cancer and radiation therapy for lung cancer were performed. Now this patient is alive without any recurrence.