The purpuse of this study is to clear the efficient of torisonal rigidity of flanges for elastic buckling strength of web plate under bending shear and axial force. The evaluation of buckling strength of plates under bending shear and axial force has already proposed, in case of simple-supported plates and clumped plate. However, web plates in real H-shaped member is not under simple-support or clumped, web plates are under a finited torisonal rigidity of flanges. Thus, it is necessary for better evaluaion of buckling strength that the effecient of this torisonal rigidity. So, in this paper, a buckling analysis of plate under bending-shear and axial force is performed, thinking the efficient of flange torisonal rigidity. This analysis is done with energy method. Then, the efficient of torisonal rigidity of flanges for elastic buckling strength of web plate under bending shear and axial force is cleared. And, new evaluation method is proposed. The accuracy of this new method is higher than that of the past method.