A 71-year-old woman underwent endoscopic submucosal dissection for early duodenal cancer at the second portion of the duodenum and developed acute peritonitis due to delayed duodenal perforation. Emergency laparotomy was performed. A huge perforation formed at the descending duodenum without ampulla involvement. Pancreas-sparing partial duodenectomy (PPD) with gastrojejunostomy was performed (250min operative time) with 50mL of intraoperative blood loss. She required intensive care for 3days and was discharged on postoperative day 21 with no severe complications. Emergency treatment for a major duodenal injury or perforation remains challenging because of high morbidity and mortality. An appropriate treatment should be considered according to the nature of the defect. Although PPD is an acceptable procedure for patients with a duodenal neoplasm, its use in emergency surgery is rarely reported. PPD is more reliable than primary repair or anastomosis using a jejunal wall, and less invasive than pancreaticoduodenectomy, for emergency treatment. We performed PPD in this patient because the duodenal perforation was too large to reconstruct and did not involve the ampulla. PPD can be a safe and feasible alternative surgical procedure to pancreaticoduodenectomy for a major duodenal perforation, especially in patients with a duodenal perforation that does not involve the ampulla.