To evaluate the seismic resistance capacity of column-beam connections of steel rigid frame structures, cyclic loading tests of column-beam connections were carried out with five specimens. Experiment parameters were the methods of calculating plate thicknesses and structural types of column-beam connections. As a result, it was found that the influence of shear lag on the resistance capacity of column-beam connections is comparatively small. In addition, the effects of haunch plates at the corner of connection were verified through FEM analysis.