The incidence of peri-stent graft infection (PGI) following thoracic endovascular aortic repair (TEVAR) is low, but the associated mortality rates are extremely high. The diagnosis of this complication can be difficult due to nonspecific symptoms. Here, we report a case of PGI combined with an aorto-esophageal fistula (AEF) diagnosed by computed tomography (CT) and positron emission tomography (PET) imaging after TEVAR. A 50-year-old woman with a history of diabetes mellitus and chronic hemodialysis had received a stent graft for a contained rupture of a pseudoaneurysm of the descending thoracic aorta. Three months after stent-grafting, she experienced back pain. CT and PET imaging suggested a PGI. The patient underwent surgical treatment for PGI with AEF.