This paper was developed to computer program, which is about to analysize nonlinear behavior of structural member and frame including to geometric and material nonlineality, and formulated to the relationship of stress-strain of steel. Also, the obtained results by this program were in accordance with existing experimental and analytical results respectively, according to numerical analysis for examples in order to examplity the efficiency of this program. The obtained results are summarised as follow. (1) The analytical results by this numerical analysis method was underestimated for the existing experiment results in maximum strength, but the obtained results by this program were in accordance with existing experimental and analytical results respectively. (2) This numerical analysis method have a problem which is to change of load near the yielding point in convergence calculation. So, it is required to improvement for this problem.