We developed a system that overlays a 3D model onto a target in a camera image, in other words, a system that can display a dismantled part directly onto a target. The system constructs a database called a "key frame database" in advance, which consists of multiple sets of a target's photo, a target's position and posture when a camera captured it, 2D and 3D coordinates and normal vectors of feature points in the photo, image patches around the feature points. At runtime, this system takes an image sequence of a target by using a camera and estimates the target's position and posture by matching the image with photos in the key frame database. A 3D model of the target is located on the current image based on the estimated position. We conducted experiments for the developed system, which evaluated an accuracy of the target's position and posture estimation, limitations of distances about overlaying the 3D model, robustness for occlusions and an update rate of the estimation. As a result, we confirmed that the system had a capacity for dismantlement work supports.