Inclusion Criteria:  Adults with 19 years of age or older Those who voluntarily consented to the trial and signed a written consent Inoperable malignant biliary obstruction  Exclusion Criteria:  Previous surgical biliary drainage Patients continuosly requiring percutaneous transhepatic biliary drainage History of biliary drainage with metal stent Biliary obstruction located in hilum or intrahepatic duct Patients with life expectancy of 3 months or less On pregnancy Unable to underwent endoscopic procedures