A 73-year-old man with rectal cancer was admitted to our hospital with a complaint of blood in his stool. Colonoscopy revealed a type 2 tumor in the lower rectum. Upper gastrointestinal endoscopy found a 0-Ⅱc lesion at the greater and lesser curvatures of the gastric body and a 0-Ⅱb lesion at the lesser curvature. Therefore, based on the diagnosis of gastric and rectal cancer, we performed simultaneous laparoscopy-assisted combined resection for both gastric and rectal cancer.Based on the diagnosis of the rectal cancer T4a, N1, M0 Stage Ⅲa, we administered NACRT. A complete response was almost achieved following NACRT. We performed the surgery after completion of NACRT.First, laparoscopic distal gastrectomy (delta anastomosis) was performed because of the necessity to determine the port positions. Next, we performed laparoscopic abdominoperineal resection after insertion of the additional ports. In this case, it was possible to extract a specimen through the perineum incision. We simultaneously performed simultaneous laparoscopic surgery for gastric and rectal carcinoma with only one incision.