A 56-year-old man with diarrhea and bloody stools was found to have a type 2 tumor in the rectosigmoid region. A biopsy revealed well-differentiated tubular adenocarcinoma(tub1), and laparoscopic high anterior resection was performed. The final diagnosis was MiNEN(NEC:adenocarcinoma=6:4), RS, type 2, Ly0, V0, pT3(SS), pN0, M0, and pStage Ⅱa. He has been followed up without postoperative adjuvant chemotherapy and has been alive without recurrence for 1 year and 4 months after surgery. MiNEN is a rare disease, and most of them are mixed with NEC components or high- grade NET G3 and have a poor prognosis. We present an important case of rectal MiNEN.