This paper proposes a new integrated optimization for comprehensively supporting two main tasks of a conceptual design : functional design and component layout design. The proposed method consists of two optimizations : functional optimization and layout optimization, and derives the optimal solutions by cooperatively executing them. The functional optimization is based on the HGA (hierarchical genetic algorithm) in order to consider a hierarchy of functional structure, whereas the layout optimization is based on the sequence-pair and can also support a hierarchy of parts assembly. Using the proposed method, both the functional structure and the components layout that satisfies performance, cost and area at a high level can be simultaneously obtained. To demonstrate the flow of the proposed method and confirm its effectiveness, this paper describes the case study, where internal devices of a personal computer are designed using the proposed method.