With the development of robot technology, the activities of robots are expected to enter the human environment. Robots in human environment need the large-scale system with multi-degrees-of freedom for environmental adaptation. Therefore, it is necessary to design a large-scale system efficiently and simply. Tsuji et al. proposed function based control method. This method decouples a large control system into small independent components called “function” extracted by the “function mode”. However, design method of function mode has not been clarified. Therefore, this paper considers the design method of function modes by fragmentation of the function mode. By using this method, independent control of complex tasks can be achieved. This method can be a guide for designing complex functions and improve the adaptability to a designer's intention and unknown environment. Proposed method is implemented in hybrid control system using three robot arms and each robot arm has two degrees of freedom. The validity of proposed method is verified by the experimental results.