A method was proposed to estimate the stress distribution in anisotropic materials in consideration of the stress change in the thickness direction with the x-ray diffraction analysis, and calculation errors of the stress was examined numerically. Stress distributions with the error of 10 MPa for the stress and 10 MPa/μm for the stress gradient can be obtained when the diffraction angle is measured with the error less than ±0.02 deg. Influences of the number of measurement and the nonlinearity of the stress distribution were also examined.