We herein report the successful case resulted to be obtained pathological complete response by the preoperative chemotherapy. Eighty two year-old female patient visited to our clinic with abdominal pain, hematochezia and anorexia. CT scan revealed the primary tumor existed occupying the pelvic cavity and suspiciously invaded to the sacrum. Several enlarged nodes were notified however there was no distant metastasis. She was diagnosed as cStage IIIb rectal cancer. Although radical resection with sacrum below S4 could achieve R0 resection, her rectal cancer was considered to be difficult to resect. Chemotherapy after stoma creation was scheduled with written informed consent. After stoma creation standard dose of mFOLFOX6 was initiated. Chemotherapy continued with 20% dose reduction due to toxicity. After 11 courses, we judged that the response of mFOLFOX6 for her rectal cancer made R0 resection possible without extended resection. Then she underwent low anterior resection with D2 (prx D3) lymphadenectomy. Resected specimen showed that microscopically Ul-IV ulcer that the ulcer bed was replaced with fibrotic tissue and the surface layer covered with regenerated epithelium was found at the primary site. Any cancer cells were not seen in the resected bowel. As for the resected lymph nodes, there were necrotic tissues replaced with xanthoma cells. No cancer cells were found as well. Pathological response of chemotherapy was judged as complete response. Twenty months passed after surgery, there is not any symptom for relapse while undergoing scheduled follow-up observation without postoperative adjuvant chemotherapy because she did not desire adjuvant therapy.