This study evaluated the prevalence and risk factors of early- (within 7 days of placement) and late-onset (after 7 days of placement) cholecystitis after Y-configured metal stent placement. Between June 2005 and August 2020, 109 patients who had been treated with Y-configured metal stents for malignant hilar obstruction were enrolled in the study. We retrospectively analyzed the potential risk factors for post-stent cholecystitis. The presence of diabetes (p= 0.042), the length of the common part of the Y-stent (p= 0.017), filling of the gallbladder with contrast medium during the procedure (p= 0.040), and tumor invasion of the cystic duct accompanied by filling the gallbladder with contrast medium during metal stent placement (p= 0.001) were identified as important risk factors. In cases of late-onset cholecystitis, stent obstruction (p= 0.004) and repeated endoscopic procedures due to stent malfunction (p= 0.024) were significant risk factors. In the multivariate logistic regression analysis, significant risk factors were the length of the common part of the Y-stent (p= 0.032) in early-onset cholecystitis and stent obstruction (p= 0.007) in late-onset cholecystitis. This study demonstrated that early-onset cholecystitis may occur in patients according to the length of the common portion of the Y-stent. In contrast, late-onset cholecystitis may occur in patients with stent obstruction.