Optimization of the layout of plane frames as well as cross sections of the members under constraints of stress and global elastic buckling is presented based on the finite-element method and sequential linear programming. The critical load of in-plane global buckling is determined based on linear buckling analysis. Unlike the conventional shape optimization of cross sections, the nodal coordinates of the members as well as cross-sectional dimensions are constituents of design variables. When stress in a certain member is extremely low, or the length of a member or a cross-sectional dimension is extremely small, the member is removed according to given rules and thus the layout of the frame is automatically altered. Some examples of the minimum weight design of plane frames are presented. They show the availability of the proposed method.