Masuda, SumioKashiwabara, ToshinobuNakajima, KazuoFujisawa, ToshioA layout problem of computer communication network is formulated graph-theoretically as follows: "Given a simple graph G = (V,E), find an embedding of G with the minimum number of edge-crossings such that (i) the vertices in V are placed on the circumference of a circle C, and (ii) the edges in E are drawn only inside C." In this paper, this problem will be shown to be NP-hard. Therefore, it is very likely to be intractable.en-USTechnical Report