Provided are a phosphazene compound, a method for preparing a phosphazene compound and a method for producing a polymer with a phosphazene compound as a catalyst. The compound of formula (I) or a solvate thereof, where A is a six- or eight-membered ring consisting of repeated P═N, and B is at least one of unsubstituted or substituted C1-6 alkylamino, unsubstituted or substituted C1-6 cycloalkylamino, unsubstituted or substituted arylamino, or halogen, and B is attached to A at phosphorus in P═N, where R is unsubstituted or substituted C1-6 alkyl, unsubstituted or substituted C1-6 cycloalkyl, unsubstituted or substituted aryl, or unsubstituted or substituted benzyl, or R forms C1-6 heterocycloalkyl together with N attached thereto.