To provide technology that reduces calculation burdens in a numerical analysis of estimating the strength of influence of an internal stress.SOLUTION: One embodiment of the present invention is a stress analysis method comprising: a first analysis step for performing elastic analysis pertaining to a numerical analysis model for elastic analysis including information that indicates a first shape of a member before deformation, information that indicates a first internal stress distribution and information that indicates physical property values, and calculating a second shape after deformation; a determination step for determining a second internal stress distribution that pertains to an internal stress in a partial target region of the member on which a computation process was carried out on the basis of internal stress in the target region indicated by the first internal stress distribution; and a second analysis step for performing elastic analysis with regard to a numerical analysis model for elastic analysis including information that indicates the second shape, the second internal stress distribution and information that indicates physical property values, and calculating a third shape that is the shape of the member after deformation when the internal stress indicated by the second internal stress distribution occurred to the second shape.SELECTED DRAWING: Figure 1