Objective To examine risk factors for and causes of severe postoperative pancreatic fistula (sPOPF) after laparoscopic gastrectomy (LG) Summary of Background Data There are few reports on POPF after LG. Methods Between February 2012 and March 2014, we examined 86 patients who underwent LG comparing them with 33 patients who underwent open gastrectomy (OG) for gastric cancer. Risk factors for severe POPF (sPOPF) of Clavien-Dindo grade IIIa or higher were examined. To investigate causes of sPOPF, we reviewed unedited video recordings of laparoscopic surgical procedures. Results sPOPF occurred to 3 patients (3.5%) after LG and 1 patient (3.0%) after OG, indicating no significant difference (p=0.901). Univariate analysis showed no significant risk factors for sPOPF after LG. By reviewing video recordings, all 3 patients with sPOPF after LG had direct pancreatic injury by ultrasonically activated device (USAD) during peripancreatic lymphadenectomy. In 2 of them, pancreas was injured while the contour of pancreas was obscured by bleeding. Durations of drain placement and postoperative hospitalization were longer for patients with sPOPF than for those without POPF or grades I and II POPF (p = 0.003, 0.018; respectively). Conclusions No risk factors for sPOPF after LG could be identified. USAD-induced direct pancreatic injury resulted in sPOPF, which significantly complicated the postoperative clinical course. Direct pancreatic injury can occur whether patient has previously reported risk factors (i.e. male, high BMI, distal pancreatectomy) or not. To prevent pancreatic injury, surgeons should manage hemostasis and keep good surgical field to recognize the contour of pancreas accurately.