Failure of mechanical members largely depends on the size and the development of plastic deformation from the strain concentration parts. In order to evaluate this plastic deformation of mechanical members, we pay attention to the surface temperature that is generated by plastic deformation. Most of the plastic energy exhausted by plastic deforming is converted into heat. Therefore, the heat generation represents the macroscopic plastic deformed intensity. In this report, the tensile deformation tests by using the plate specimen with a center crack were performed and the distributions of surface temperature under the plastic deformation and crack propagation were measured by the thermocouple and the infrared thermo camera. Furthermore, FE elasto-plastic analysis couples with transient heat conduction was performed. The analytical results were good agreement with the experimental ones and it was shown that the infrared thermography method was effective non-contact measurement system as the macroscopic evaluation of the plastic deformation.