A group of polyfunctional oxetane-based compounds having a structure as represented by general formula (I) or a product obtained by a reaction between a compound of general formula (I) and epichlorohydrin, an ester compound, or an isocyanate compound. When these polyfunctional oxetane-based compounds are used as cation polymerizable monomers in combination with an epoxy compound, the curing speed is high, and the cured product has highly excellent hardness, flexibility, adherence, and heat resistance.