We herein describe a case of gas-forming pyogenic liver abscess following transcatheter hepatic arterial embolization (THAE) for an iatrogenic intrahepatic pseudoaneurysm in a 74-year-old woman. Hemobilia developed 19 days after percutaneous transhepatic cholangio-drainage was performed for the purpose of percutaneous cholangioscopic lithotripsy for the treatment of post-gastrectomy choledocholithiasis. Celiac arteriography disclosed a saccular aneurysm in the right hepatic artery. The pseudoaneurysm was successfully occluded by THAE with gelatin powder and a stainless steel coil of the Gianturco type. Ten days after successful THAE, abdominal computed tomography revealed a gas-containing cavity, which suggested the presence of a gas-forming abscess, in the posterior hepatic segment, and percutaneous transhepatic abscess drainage was performed. Thus, impaired hepatic perfusion following effective THAE and coexisting cholangitis may play an important role in the development of a gas-forming pyogenic liver abscess.