Inclusion Criteria:  Patient who submitted a written informed consent for this trial, and aged between 18-90 years old Patient who have naïve papilla (no previous procedure was performed at ampulla) Patient who is suspected to have a biliary obstruction or biliary disease Patient who is needed to have endoscopic retrograde cholangiopancreatography for treatment of biliary obstruction Patient who have risks of post-endoscopic retrograde cholangiopancreatography p  Exclusion Criteria:  Patient who is pregnant Patient with mental retardation Patient allergic to contrast agents Patient who received sphincterotomy or pancreatobiliary operation previously Patient who have ampulla of Vater cancer Patient who have difficulty for the approach to ampulla due to abdominal surgery including stomach cancer with Billroth II anastomosis  Patient who have pancreatic diseases as bellow (at least one more);  acute pancreatitis within 30days before enrollment idiopathic acute recurrent pancreatitis pancreas divisum obstructive chronic pancreatitis pancreatic cancer Patients with Type-1, non-protruding Type-2 and Type-4 papilla