This paper presents an automatic design method for piping arrangement. A pipe, arrangement design problem is proposed for a space in which many pipes and objects co-exist. This problem includes large-scale numerical optimization and combinatorial optimization problems, as well as two criteria. For these reasons, it is difficult to optimize the problem using usual optimization techniques such as Random Search. Therefore, multi-objective genetic algorithms suitable for this problem are developed. The proposed method for optimizing a pipe arrangement efficiently is demonstrated through several experiments.