A dividing position and integration of automotive parts determination method includes: acquiring an automotive body model including automotive parts modeled by elements and joining points at which the automotive parts are joined as a parts assembly; setting objectives related to automotive body performance of the automotive body model, constraints related to a volume of the automotive body model, and load and constraint condition or only loading condition given to the automotive body model, and obtaining sensitivity of each of the elements in each of the automotive parts satisfying the objectives under the load and constraint condition or only the loading condition and the constraints; and determining a position where the automotive part is divided and/or the automotive parts to be integrated based on the sensitivity of each of the elements in each of the automotive part.