A 24-year-old man who had left ventricular (LV) false aneurysm, which is caused by mitral valve infective endocarditis, underwent aneurysmectomy, direct closure of aneurysmal mouth and concomitant mitral valve replacement. Post-operative course was uneventful. It has been reported that the etiology of this false aneurysm was due to the vegetations' friction, which could have caused an initial endocardial ulceration that progressively expanded into the myocardium. The false aneurysmal wall should be completely removed in order to eliminate the possibility of recurrence of the infective endocarditis. We believe that the surgical treatment should be carried out as soon as possible after completion of diagnosis because the aneurysmal wall is usually quite thin and could rupture easily.