This paper is a study of the buckling length of columns for the case of subjecting the axial forces corresponding to the overturning moment to the frames whose nodes horizontal displacement is not constrained. In this case, it is shown that taking a column length to the buckling length becomes safe side evaluation, unless the rotational resistance of both sides of columns is low. Moreover, about the buckling length in that case, it is shown that axial deformation of columns may influence to it, and more exact consideration can be performed by considering axial deformation of columns.