Present paper describes an image measurement system for the wave height distribution around ship hulls in regular wave. The wave profile on a laser light sheet is visualized by the difference of light scattering between air and water. Detecting the boundary of bright and dark area on the visualized image with an image processing technique, the instantaneous wave profile on the sheet illumination is obtained. The wave height distribution in calm water can be obtained by reconstructing the distribution from the measured time-series data on a computer. The conditional sampling technique enables to obtain the wave height distribution in regular wave. The wave pattern around a ship in regular wave changes periodically, and its period is based on the encountering interval of wave and ship hull. The measured time-series wave profiles are sorted using their positions on the model fixed coordinate system and phases of encountering. It is the first try to obtain the time series wave pattern based on an experiment.