Neutron diffraction technique was employed to measure stress distribution in an interior region of a SUS304 rotating mechanical component with a fringe after solution treatment and after subsequently conducted stress-relief annealing. A coupon with 3x3x3 mm was prepared by spark cutting to determine stress-free spacing d0. The elastic strain was determined by using the measured (111) spacing d and d0 by (d - d0)/d0. Then the obtained strains were input into the general Hooke’s law to calculate stresses. The residual hoop stress near the surface is compressive which is lowered in the inner part. The residual stresses near the center of the component are hydrostatic tensile stresses. These residual stresses were not relaxed by the annealing treatment recommended in a handbook. Hence, more appropriate stress relief treatment has to be developed. In case of a cast specimen, coarse grains with a strong texture made it difficult to determine residual stresses precisely.