1. A three-dimensional model data generation device that generates three-dimensional model data of a data format representing a three-dimensional object for making a solid three-dimensional model of an object which includes a plurality of structural elements from three-dimensional image data representing a three-dimensional image of the object with a three-dimensional model making device by using predetermined material, wherein the three-dimensional model making device forms physical layers of the predetermined material one on top of the other according to the three-dimensional model data to make the solid three-dimensional model, the three-dimensional model data generation device comprising: a memory configured to store computer-executable instructions; and a processor configured to execute the stored instructions, causing the processor to perform the following operations: adding a textured pattern of protrusions and recesses to at least one of a surface of the object represented by surface data of the object and surfaces of the structural elements represented by surface data of the structural elements generated from the three-dimensional image data; and generating the three-dimensional model data by combining the surface data of the object and the surface data of the structural elements including the surface data to which the textured pattern of protrusions and recesses is added, wherein, when a determination is made that a structural element is in contact with none of other structural elements, the three dimensional model of the structural element is generated separately from the other structural elements, and based on the determination, a graphical connection between the structural element and at least one of the other structural elements is added to the three-dimensional image data, and wherein, if the structural element is a blood vessel or a bronchial tube, the blood vessel or the bronchial tube is extracted using a technique which generates tree structures by connecting nodes.