his paper aimed to understand the residual stress in the dissimilar metal welds of nuclear power plant. Two kinds of residual stress were considered, which caused by welding and machining. Residual stress due to mechanical machining was measured by hole-drilling technique and x-ray diffraction method for the SA508 and F316L. Weld residual stress at dissimilar metal weld between SA508 and F316L was evaluated by FEA. Residual stress profiles were obtained for the inside surface and through thickness of welds. Machining effect was also analyzed by FEA. According to the residual stress measurement, it was observed that mechanical machining can generate tensile stress on the surface of the test material. However, FEA results showed that mechanical machining did not increase the tensile stress on the surface of weld region. Further study with more elaborate measurement and numerical analysis is required to identify the effect of machining on residual stress in the dissimilar metal weld region.