Recently, light weight structure becomes an object of attention because increase of energy efficiency becomes the most important global hot issue. Then, composite structures, which have inherent high strength and stiffness to weight ratio, are in the limelight for light weight structures. However, complex failure modes of composite structure are still remains unsolved problem and become main obstacle of wide application of composite structures. Delamination is one of frequent damage phenomenon of laminated composite structure. Delamination can cause reduction of structural stiffness and decrement of natural frequencies. This might induce increase of structural vibration and resonant phenomenon of operating structures. Then, delamination should be detected and complemented. In this work, active control scheme and piezoelectric actuators are used to reduce the delamination effect of damaged composite structure. At first, finite element model for delaminated composite structure is constructed based on improved layerwise theory and then state space control model is established. After design and implementation of active controller, dynamic characteristics and structural performances of damaged composite structure are investigated and effectiveness of active healing is evaluated.