Residual stress is generated in the structures as a result of irregular elastic-plastic deformation during fabrication processes such as welding, heat treatment, and mechanical processing. There are several factors attributed to the origin of residual stresses, tensile or compressive. The stresses can be determined by destructive ways or nondestructive ways using X-ray or neutron diffraction. Although X-ray diffraction is a well established technique, it is practically limited to near-surface stresses. Neutrons penetrate easily into most materials and neutron diffraction permits non-destructive evaluation of lattice strain within the bulk of large specimens because the radiation is more deeply penetrating for metallic engineering components. This paper presented application of neutron diffraction technique to the residual stress measurement using 20 mm thick welded stainless steel plate($100{ imes}100 extrm{mm}^2$)