To connect a plurality of pipes for a large structure such as an electic overhead line support to each other rapidly, easily and accurately with small number of components and few work mandays without a protruding part.

In this pipe connecting structure 10 for a large structure, contracted parts 14 and mutually retrorse external thread parts 16, 17 on the outer peripheral surfaces of the contracted parts 14 are formed at the respective end parts of vertical and bent pipes 4, 6 formed of an aluminum alloy. The contracted parts 14 of the pipes 4, 6 are coaxially opposed to each other in a longitudinal direction, and mutually retrorse internal thread parts 22, 24 formed at the inner peripheral surface of a connecting cylinder 20 of the same diameter as the pipe 4 are thread-fastened to the external thread parts 17, 16 to connect both pipes 4, 6 while drawing them to each other. An electric overhead line support 1 is built up by connecting a plurality of pipes 4, 6, 8 using this connecting structure 10.