Duodenal gastrointestinal stromal tumors (GISTs) are relatively rare, and the optimal surgical strategy in such cases remains unclear. Various techniques have been described for limited resection of duodenal GISTs, depending on the site and size of the tumor, and the developmental morphology. We herein report a 70-year-old man who presented with a tumorous lesion near the pancreas by an abdominal ultrasonography at a medical checkup. It was diagnosed as a GIST showing an extramural growth, involving the first portion of the duodenum by endoscopic ultrasound-guided fine needle aspiration (EUS-FNA). We employed a laparoscopic surgical technique using a retrieval bag, with which we covered the tumor, and applied tension to it to enable a safe and easy tumor resection at its base with an automatic suture device. Histopathological findings showed a low-risk GIST with a negative surgical margin. This report highlights that a use of a retrieval bag from beginning of the resection facilitates easy laparoscopic partial resection of extramural duodenal GISTs without injuring the pseudocapsule of the tumor.