This system is a system for analyzing blood flow of a target vascular site by means of simulation, having a fluid analysis unit, by a computer, for determining state quantities of blood flow at each position of a lumen of the target vascular site by means of computation by imposing computational conditions including boundary conditions relating to the blood flow to three-dimensional shape data of the target vascular site； a three-dimensional shape modification unit for modifying the three dimensional shape data by simulating a surgical treatment method and for outputting the three-dimensional shape data after the modification； and a comparison display unit for displaying computed results of before and after the modification of the three-dimensional shape for comparing the results, by causing the fluid analysis unit to re-compute the state quantities based on the three-dimensional shape data after the modification.
