Deterioration of reinforced concrete deep beam structure caused by chloride is severe andtakes up wide area even though the structure is not exposed to sea water or brackish water. Even the structure which is far from sea water or brackish water is affected by this problem.When the reinforced concreate deep beam structure is affected by chloride steel reinforced inside the structure is corroded resulting in reducing the cross-sectional area of the reinforced steel affecting load capacity deflection and beam failure. If there is no repair or strengthening such capabilities are continuously reduced until it is no longer safe to use the beam. Therefore it is necessary to repair or strengthening the deteriorated structure to be safely used. This research investigated strengthening of deteriorated reinforced concrete deep beam caused by chloride with 4 formats of carbon Fiber sheets to seek guidelines for the most efficient strengthening. The resultshowed that the strengthening by the 4 format of carbon fiber sheet could increase ultimate loadcapability yet could not improve ductility of the deteriorated beam to become close to the beamthat is not deteriorated. The strengthening that could increase the maximum ultimate load capability was the table format strengthening. In addition the strengthening that the carbon fiber making 45 degrees with the length of the beam could best prevent diagonal cracks.