There is provided a marker selection program for selecting a marker for use in genetic diagnosis. In the program, analysis is carried out by using at least two specimen databases which respectively store data of specimens belonging different populations. By carrying out analysis without integrating all specimen data into single population, information on a minority population can be surely reflected to a gene search. Since the characteristics of each population can be reflected, high-accuracy diagnosing functions can be obtained, providing a practical diagnosing system.