Most of the plating of ship structure is stiffened by inverted angles, and the strength of these stiffeners have been estimated by the simple beam theory. However, their bending rigidity and strength may be considerably reduced because of the unsymmetry of their cross sections. In order to explain these phenomena, elastic behaviour of the inverted angle with plating under bending load was analysed considering effects of distortion of its cross section and torsion. While, to examine the validity of the theory, bending tests were carried out and fair agreements between test results and calculated values were obtained. From these results, the relation between effectiveness and ratio of breadth to thickness of the angle was found.