Detecting impact damages in real-time is an important concern for keeping up structural integrity of aerospace composite structures since impact damages may cause extreme degradation of material strength like compression after impact. The information of impact force should be a considerably significant indicator in an evaluation of damages. As a real-time structural health monitoring, the present paper proposes an identification method of impact damages in CFRP structures based on the experimental impact force identification. In a low-velocity impact event, the relationship between impact force history and corresponding strain responses in CFRP structures can be determined experimentally by an impact test using impulse hammer. Based on the relationship, the force location and the force history were identified with the strain responses measured at multiple points in a structure. The present paper develops a real-time evaluation method of impact damages such as delamination or matrix cracking using the information of impact forces obtained by impact force identification.