Conformational analysis of the reactant, product, and complex of the polymer and macrocyclic catalyst (PdMC) was carried out in order to investigate the reaction mechanism of the intramolecular cyclization reaction of the polymer chain having a Rotaxane structure. Focusing on the N-C distance of the intramolecular cyclization reaction coordinate, a group of stable conformers with short N-C distances for the reaction was found. By forming a complex with PdMC, the conformations of the reactant with a short N-C distance were stabilized and the intramolecular cyclization reaction was promoted.