In this study, a newly developed wave-visualized technique was applied to impact damage detection in scarf-repaired composite. This technique can make it possible to visualize the ultrasonic wave propagation in scarf-repaired composite. When propagating waves scatter or reflect at the damage area, we can detect damages by observing the visualized wave propagation. Scarf-repaired composites with an artificial defect simulating impact damage were inspected by using this wave-visualization technique. Simulation and inspection of specimens with coating were also done for evaluating influence of coating on the damage detection using this wave-visualization technique. As a result, scattering and reflection of visualized ultrasonic waves were observed around the damage area in scarf-repaired composites with or without coating. This result indicates the wave-visualized technique is useful in inspection of scarf-repaired composites.