Unique folded structures of natural and synthetic oligomers are the most fundamental basis for their unique functions. N-Substituted beta-peptides, or beta-peptoids, are synthetic oligomers with great potential to fold into diverse three-dimensional structures because of the existence of four rotatable bonds in a monomer with highly modular synthetic accessibility. However, the existence of the four rotatable bonds poses a challenge for conformational control of fi-peptoids. Here, we report a strategy for per-residue programming beta two dihedral angles of beta-peptoids, which is useful for restricting the conformational space of the oligomers. The oligomer was found to form a unique loop conformation that is stabilized by the backbone rotational restrictions. Circular dichroism and NMR spectroscopic analyses and X-ray crystallographic analysis of the oligomer are presented. The strategy would significantly facilitate the discovery of many more unique folded structures of beta-peptoids.