In this paper. we propose and implement an 3D measurement system by using defocus images obtained from a single camera. Depth from Defocus (DFD) is one of methods to estimate depth information from a pair of two defocus images. In former researches, target object to be measured must be inside between the two images. We propose an algorithm to overcome the limitation, and have implemented the system by a high-speed camera and telecentric lens. We verified the efficiency of the proposed system by some experiments.