Ship's crews seem to be more interested by hull bending deflection than stress or strain of structural members. The authers have developed a monitoring apparatus for visualization of dynamic bending of ship's hull. It makes use of a scanning laser-light beam and photoelectric cells. Bending deflection curve is shown dynamically on a panel of the controll unit in the wheel room. Actual tests were conducted successfully on a 116, 000 DWt ore carrier on the span of about 190 meters. Statical deflection caused by loading and unloading of cargo ore and the deflection due to temperature difference were also measured. These data showed rather good coincidence with the calculated values.