Hull structure design has recently become more and more important. Ship hull structure design has always been considered, technically as well as economically, to be a very important part of the shipyard management, since the strength of a ship is concern and the cost of the hull steel is about 20% of total ship’s cost. Therefore, a good executive needs many talented designers to assist especially in hull structure design. In this chapter, philosophy of hull structure design is discussed from various viewpoints, including historical overview of the environments surrounding ship structure design such as worldwide shipbuilding production and ship size increase, procedures and policy of ship structural design, and reliable design based on the identification of loads and strength of ship structures.