PROBLEM TO BE SOLVED: To provide a data structure of a biological data model capable of processing very quickly by performing contact determination between mutual organs, and narrowing in an early stage, organs each site of which has a possibility of contact.SOLUTION: A three-dimensional data model is organized from medical image data. Pairing image files are selected from an image data file of an operation object patient, and an organ as each site constituting an organism in a prescribed range, and a simple geometric shape enclosing the organ are included, and the three-dimensional data model is organized in a tree shape by each joint for specifying a positional relation between the respective organs.SELECTED DRAWING: Figure 23