Abstract: It is known that sport skill learning is facilitated by observing images of photographs of movements of trainees themselves or images of exemplary motions. However, observation learning of images is not used routinely at ordinary sports practice sites. The main hindrance blocking the wider use of images is that “it is troublesome to detect an objective scene from image files”. This study was conducted to establish a technology for the retrieval of objective scenes from images of body action based on three-dimensional point cloud processing and to propose an assist method for observation learning using this technology. In this study, coaching of karate-kata is emphasized, along with automatic retrieval of images of karate-kata and karate-kata practice assistance methods.