Mycotic aneurysm of the superior mesenteric artery (SMA) is a rare complication of infective endocarditis. We report a case with infective endocarditis involving the aortic valve complicated by multiple septic embolisms. The patient was treated with antibiotics for 6 weeks. During preparation for surgical treatment, the patient developed acute abdominal pain and was diagnosed with a ruptured SMA aneurysm, which was successfully treated with an emergency operation of aneurysm ligation. The aortic valve was replaced 17 days later and the patient recovered uneventfully. In conclusion, we present a rare case with infective endocarditis (IE) complicated by SMA aneurysm. Antibiotic treatment did not prevent the rupture of SMA aneurysm. Abdominal pain in a patient with a recent history of IE should be excluded with ruptured aneurysm.