Photocationic polymerization of epichlorohydrin in the presence of dimethylphenacylsulfonium hexafluorophosphate was carried out. Polymerization behaviors and the molecular structures of resulting polymer were discussed in relation to the reaction parameters such as the degree of dryness, initiator concentration, dark reaction time, temperature and duration of photoirradiation. The kinetic studies revealed that the % conversion to polymer during the photoirradiation is negligible and the polymerization mainly proceeds in the dark reaction period which implies the living nature of this polymerization system. However, the presence of initiator fragments at the end group of the polymer, confirmed by spectroscopic analysis indicated that the initiator takes a role not only in the initiation but also in the termination, which denies the true living nature of this polymerization system. A possible polymerization mechanism was proposed, based on the kinetic and spectroscopic results.