A process for the preparation of cyclododecanone by subjecting an epoxycyclododecane−containing raw material to isomerization in the presence of an isomerization catalyst containing lithium bromide and/or lithium iodide, wherein a product which is obtained by bringing epoxycyclododecadiene into contact with hydrogen in the presence of a hydrogenation catalyst and has a content of hydroxyl−bearing cyclododecane compounds of 5 mole % or below is used as the epoxycyclododecane−containing raw material in order to conduct the isomerization efficiently (at a high reaction rate) with high selectivity and thereby prepare high−purity cyclododecanone industrially stably with the reaction rate kept at a high level.
