As one of the characteristics of ship hull structure, many holes are made on web plates for access and weight saving. On the first report, the authors studied the instability of perforated plate under shearing force by means of FEM analysis and experimentation to determine the effects of stiffening on the buckling strength. The study dealt with the simply supported plate having oval form perforation and reinforced with stiffener, spigot-plate or doubling. On this paper, we deal with the girder models coincident with ship structures. The object of this study mainly accounts for the buckling strength of doubling plate, because in the first report, some discrepancy was found between the results of experiment and FEM analysis. The conclusion drawn are as follows ; 1) As far as this study, the order of shear buckling strength are as follows. Insert >Spigot-plate>Stiffener≈Doubling 2) In general, stiffener may be selected for the most plactical method for reinforcement and the design strength of reinforced plate with stiffener can be estimated from the plastic collapse strength of the web with perforation. 3) In the case of doubling reinforcement, the eccentricity of the reinforced part takes adverce effect on the buckling strength considerably.