A 79-year-old male with diabetes mellitus and old cerebral infarction was admitted to hospital due to fever and palpitation. Diagnosis of purulent pericarditis was established by pericardial effusion examination. The patient’s general condition improved temporarily after drainage of the pericardial effusion. However, computed tomography demonstrated a saccular aneurysm arising from RCA have rapidly grown even larger, up to 63 × 51 mm on 7th hospital day. This indicated that the risk of rupture of the aneurysm was high. Percutaneous coronary intervention was applied to prevent rupture of the aneurysm. Several polytetrafluoroethylene (PTFE)-covered stents were required to cover the extended aneurysm lesion. A long drug-eluting stent (DES), which was initially implanted through the aneurysm, was itself implanted with 3 PTFE-covered stents located inside the DES. This procedure provided protection against endoleak of the aneurysm. To our knowledge, the present case shows for the first time that PTFE-covered stents located within DES are useful in treatment of a giant coronary aneurysm.