A computer reads data from a database in an external recording device to generate an analysis model which represents the surface profile of a member with a mesh. Next, the computer initializes the meshes of the analysis model by setting thereto a gas attribute corresponding to a non-leakage site and thereafter sets to any mesh a liquid attribute corresponding to a leakage site, and changes the attribute of meshes adjacent to the meshes having the liquid attribute from the gas attribute to the liquid attribute. Then, the computer connects meshes of which attribute has been set to the liquid attribute to generate a leakage path and outputs information relating to the leakage path on a display device.