A 51-year-old man admitted to our hospital because of an ECG abnormality pointed out by his local doctor. He had been hospitalized for scarlet fever at age 10. A coronary artery CT scan showed coronary artery aneurysm of the left main trunk (LMT), and coronary angiography showed 3-vessel disease including a chronic total occlusion of the right coronary artery (RCA). We performed conventional coronary artery bypass grafting (CABG) using an arterial graft and aneurysmectomy. The patency of the graft was confirmed by coronary angiography postoperatively. The pathological diagnosis of the coronary aneurysm was Kawasaki disease. CABG is a standard procedure for coronary artery aneurysms with Kawasaki disease. However, there are no established treatment guidelines on whether to perform aneurysmectomy. We chose CABG with aneurysmectomy because of the possibility of intra-aneurysmal thrombosis leading to peripheral occlusion, and the cause of the coronary artery aneurysm could not be determined. However, even if additional treatment by percutaneous coronary intervention (PCI) is not possible, it is important to avoid occlusion of the graft.