The chain structure of cis-poly(4’-ethynylbenzo-15-crown-5) (PEB15C5), prepared using the rhodium complex catalyst, was studied at -175 degrees C using the solid-state NMR technique. The second moment of PEB15C5 was 7.0 G(2) for the main chain and 19.0 G(2) for the side chain. These values agreed well with the respective theoretical ones for the cis form in the rigid state rather than the traits one. This agreement between experiment and theory suggested that the plane of the side chain (i.e., the benzo-15-crown-5 group) is orthogonal to the main chain plane of the cis-transoidal form. It was verified that the strong dipole-dipole interaction between the side chains plays an important role as a clue to theoretically determine the cis-transoidal form. NMR results in solid state confirmed theoretically that multipeaks in the H-1 and C-13 NMR spectra in CDCl3 solution are attributed to cis-transoidal form in the chain.