A 74-year-old man was admitted to our hospital with chest pain and dyspnea associated with ST elevation in leads II, III and aVF. An echocardiogram showed an enlarged mass lesion measuring nearly 80 mm. Coronary angiography showed two giant coronary artery aneurysms (CAAs) in the right coronary artery (RCA). CAAs were also seen in the left main trunk and left anterior descending artery. Computed tomography showed the CAA in the RCA was ruptured into the right atrium. We therefore diagnosed this patient with multiple CAAs, myocardial infarction and coronary artery rupture. He underwent successful surgical excision and coronary bypass surgery.