The patient was a 57-year-old male. He was diagnosed with locally advanced rectal cancer infiltrating the left levator ani muscle. Chemotherapy(S-1 plus L-OHP plus bevacizumab regimen)was started for the purpose of obtaining a negative circumferential radial margin. After the second course, he presented with perforation of the sigmoid colon for which an emergency operation was performed. The perforation was located 5 centimeters above the tumor in the sigmoid colon. We performed partial resection of the sigmoid colon to repair the perforation and create a sigmoid colostomy. CT, after the initial S-1 plus L-OHP plus bevacizumab chemotherapy regimen, revealed tumor shrinkage. Following 2 more courses of chemotherapy( S-1 plus L-OHP regimen), we performed transanal total mesenteric excision(taTME)as curative surgery. R0 resection was achieved. The combined transanal and laparoscopic approach was highly effective for a patient with pan-peritonitis.