An approximately 50-year-old man with rectal cancer(RbP)[ cT3(cA), cN3, cM0, and cStage IIIb] who desired anus preservation was administered mFOLFOX6 therapy. This treatment decreased the size of both the tumor and the lymph node, and intersphincteric resection (ISR) was performed. Histopathology demonstrated tumor invasion beyond the muscularis propria, and the histological effectiveness was Grade 2. Because computed tomography showed an abscess in the dissection area, we performed postoperative drainage and the patient recovered. Therapy with mFOLFOX6 was repeated after the patient was discharged from hospital. Increased adoption of anus-preserving surgery is expected via successful control of local recurrence and distant metastasis by neoadjuvant chemotherapy.