Buckling and collapse of the curved corner structure are investigated by model tests and FEM buckling analysis. And it is discussed how stiffener arrangement and load condition have effects on buckling and collapse load, and collapse mechanism. The results are summarized as follows : (1) Radial stresses have a significant effect on panel buckling in some cases. (2) Local or overall collapse takes place according as a face bar is supported or not. (3) P_cr / P_y and P_ult / P_y depend on load condition. P_y is a calculated load at which a face bar starts to yield. (4) Buckling and collapse load for one stiffener arrangement may be 20% less than those for another arrangement with the same total length of stiffeners.