The inverse method applied successfully to several basic structures was extended to estimation of impact stress intensity for point bend specimens. The response functions of the specimens were estimated by de-convolving the specimen response measured near the crack tip with the measured impact force. Two methods for deconvolution were used, e.g., a simple statistical method and a CG-FFT iteration method. The ill-posed nature of the deconvolution was removed successfully by the CG-FFT method and then the excellent estimation was obtained.