In the previous report, the authors investigated the interaction between deckhouse and main structure, and in this paper the elastic behaviour of superstructure was researched. In the case of superstructure whose sides are continuous to the side shell, the interaction between superstructure and main structure depends on the tensile (or compressive) rigidity of their side plates in the vertical direction, while in the case of deckhouse the vertical reaction between house and hull is affected by the bending stiffness of the upper deck. Then an evaluating method of the stiffness factor for superstructure was presented. The method for estimating the effective area of deckhouse shown in the previous report was examined to be applicable to that of superstructure by the comparison of the calculated values with the measured values which were obtained by the various model experiments. Using the stiffness factor and the effective area evaluated by these methods, the result of the bending test of aluminium superstructure was analysed. The simplified formula for the bending calculation of the superstructure was presented and its numerical values were compared with results calculated by the successive approximate method and the validity of the formula was discussed.