We have developed a computer program which is able to treat three-dimensional information on defects in composite materials. The information on defects was constructed by combining the echo level of the reflector plate method and beam path distance of the pulse reflection method. As an example, the proposed method was applied to GFRP and CFRP laminates including artificial defects. Three-dimensional information on defects was obtained, and the images of defects were visualized by the newly developed computer program. The images generated for defects were so clear that the size and location of each defect could be recognized easily. From these results, it can be shown that the method proposed in this paper is very useful in evaluating defects in composite materials.