A 69-year-old woman was given a diagnosis of moderate aortic stenosis (AS) associated with congenital bicuspid valve in 2011. In 2014, surgery was indicated because of progression of AS and dilatation of the sinus of Valsalva and ascending aorta. Preoperative contrast-enhanced CT and echocardiography showed the saccular space (2×2 cm) located at the left ventricular outflow tract just below the aortic annulus. At surgery, the saccular aneurysm was located just below the aortic annulus of the noncoronary cusp. We resected the aneurysm and closed the orifice with interrupted sutures from the inside of the LV and the outside. Aortic subannular left ventricular aneurysm is a very rare malformation with only 25 reported cases and its natural course is largely unknown. Rupture of aneurysms, infection, thrombus formation, arrhythmia, and heart failure etc. has been reported as complications. We reported a case of aortic subannular left ventricular aneurysm with bicuspid aortic valve stenosis with a literature review.