Effect of endoscopic sphincterotomy (ES) prior to metallic stent (MS) placement in patients with distal malignant biliary obstruction (MBO) to prevent post-ERCP pancreatitis (PEP) remains to be fully elucidated, because the safety of non-adding ES for the cases without main pancreatic obstruction is unclear. To evaluate the efficacy and safety of non-adding ES prior to MS placement in patients with distal MBO, including those without MPD obstruction. Between January 2006 and August 2017, 285 patients with distal MBO were treated with MS placement in our tertial referral center, of which 74 were excluded because of a former history of ES, and/or prior MS placement. Finally, 211 patients were retrospectively enrolled in this study. Sixty-nine patients underwent ES just before MS placement (ES group), whereas 142 underwent MS placement without ES (non-ES group). We evaluated (1) the patients’ characteristics, (2) the incidence of PEP within 2 days after the procedure, (3) the incidence of bleeding, cholangitis, cholecystitis, and perforation within 30 days after the procedure, and (4) the effect of ES/ non-ES on the time to MS dysfunction. (1) Sex (man): ES, 40; non-ES, 83 (p = 0.947). Age (median): ES, 71 (range, 11–89); non-ES, 67 (range, 43–90) (p = 0.659). The etiology of MBO (bile duct cancer/ gall bladder cancer/ lymph node metastasis/ pancreatic cancer/ ampullary cancer): ES, 12/4/12/41/0; non-ES, 14/3/12/107/6 (p = 0.018). MPD obstruction: ES, 43; non-ES, 117 (p = 0.019). (2) PEP occurred in 11 patients in the ES group and in 20 in the non-ES group (p = 0.721). Among the patients without MPD obstruction (26 in the ES group and 25 in the non-ES group), PEP occurred in 10 patients in the ES group and in five in the non-ES group (p = 0.148). (3) Bleeding was significantly higher in the ES group (three patients) than in the non-ES group (zero patient, p = 0.034). Further, the incidence of cholangitis (four vs. five patients, p = 0.13), cholecystitis (four vs. four patients, p = 0.497), and perforation (zero patient in both) in the ES and non-ES groups, respectively, was not significantly different. (4) The median follow-up periods in the ES and non-ES groups were 191 (range, 14–999) and 204 (range, 12–1846) days, respectively. MS dysfunction was observed in 15 and 30 patients in the ES and non-ES groups, respectively (p = 0.919). The median time to MS dysfunction in the ES and non-ES groups was 145 (range, 6–465) and 114 (range, 2–759) days, respectively (p = 0.803). The study concluded that performing ES prior to MS placement for distal MBO does not reduce the incidence of PEP, but elevates the risks of bleeding related to ES. Hence, routine ES should be avoided prior to MS placement for distal MBO.