We report a mitral valve repair for a broad prolapse in the high posterior leaflet. Prolapse in the high redundant posterior leaflet with elongation of the chordae had caused the severe mitral valve regurgitation in a 45-year-old man. At operation, the prolapsed portion of the middle scallop was quadrangularly resected in 22 mm wide and 17 mm high. We combined the sliding leaflet technique with the posterior leaflet folding plasty to reduce the height of the posterior leaflet and to lessen the degree of mitral annular plication. Mitral valve regurgitation disappeared after the operation. No left ventricular outflow obstruction associated with systolic anterior motion and no injury to the left circumflex artery were confirmed. These procedures after a broad resection of the high posterior leaflet could successfully prevent systolic anterior motion and injury to the left circumflex artery, and reduce the stress on the suture line of the leaflet.