[Solution] This system is a bloodstream analysis system that sets a boundary condition concerning bloodstream on three-dimensional shape data of a targeted blood-vessel site in a subject, divides the lumen of the targeted blood-vessel site into meshes, and finds, by computation, the state quantity of the bloodstream at each mesh position. In this system, a computer comprises a labeling unit that reads in the three-dimensional shape data of the lumen of the targeted blood-vessel site and labels blood-vessel elements included in the targeted blood-vessel site in accordance with the size of the cross-sectional area of each blood-vessel element, the computer executing the computation of said state quantity by changing the detail level of the mesh division for each blood-vessel element in accordance with the labeling based on the size of the cross-sectional area.
