Conventional structural optimization methods are difficult to apply to the early process of design referred to as conceptual design, in which diverse design solutions are to be obtained. This paper described a design method that obtains diverse design solutions. As a first step, a form-generation system that generates diverse forms is proposed. In this case, the diversity of organism was noted, and the form-generation method was referred to ‘induction’ and ‘apical dominance’ in the developmental process of organism. The proposed system, consisting of a generation process and an optimization process, was applied to the structural design of chairs, and the diversity of solutions was analyzed. As a result, it is shown that, as compared with conventional structural optimization methods, the proposed method obtains design solutions of adequate diversity. The results indicate the effectiveness of the proposed system for obtaining diverse design solutions.