We report a case of advanced aortic sinus aneurysm without the aggravation of aortic valve regurgitation after a simple reduction procedure for dilated aortic root base and sinotubular junction (STJ) in a Marfan patient with annuloaortic ectasia and severe aortic valve regurgitation. The aortic valve competence was well preserved by limited change of distances among the interleaflet triangles after reduction of the dilated aortic root base and STJ in the Marfan patient, although the sinus dilatation was aggravated.