A computer generates an analysis model in which an object is represented by meshes. When attributes of the meshes corresponding to space which possibly becomes a cause of residual fluid are set to a first substance causing the residual fluid, the attribute of the mesh corresponding to the boundary between the object and outside of the object and corresponding to the space is set from the first substance to a second substance of which specific gravity differs from that of the first substance. Then, the attribute is changed from the first substance to the second substance according to attribute of the mesh exists in the periphery, assuming the meshes of which attribute is set to the first substance as a processing subject. Accordingly, the presence or absence of residual fluid is determined according to the presence or absence of the meshes of which attribute is set to the first substance.