In design of port structures, it is very important to set up all design conditions reasonably in view of reasonable design. However, it is the real situation now that all design conditions are not set up in the same accuracy and rationality. In this background, the authors took the focus to surcharge, one of the important design conditions. The authors investigated the influential degree of surcharge, the utilization of apron and examined reasonability of decision method of surcharge.
　As a result of these investigations, the authors presented several decision methods of surcharge.