A biological model generating apparatus establishes, for each of a plurality of nodes on a centerline of a blood vessel, based on blood vessel information, a first circle and a second circle on a plane cutting through the node and intersecting the centerline at a right angle. The first circle centers at the node and has a first radius obtained by adding a margin of error to the radius of the blood vessel. The second circle centers at the node and has a second radius obtained by subtracting the margin of error from the radius. Subsequently, the generating apparatus generates an implicit function defining a curved surface that intersects the plane cutting through each of the plurality of nodes, at the inner side of the first circle but the outer side of the second circle. Then, the generating apparatus generates a mesh model based on the defined curved surface.
