Method of identifying a valid flow path includes: performing fluid analysis of a porous body, which is ought to have inflow surface and outflow surface, based on structure data representing a 3-dimentional structure of the porous body to generate data indicating at least a pressure distribution of a fluid in a flow path in the porous body; and identifying a valid flow path that allows the fluid to flow from the inflow surface to the outflow surface based on a gradient of pressure values along a flow direction of the fluid in the flow path.