The present invention relates to a method of preparing cyclododecanone. According to the present invention, a method of preparing cyclododecanone which allows implementation of a high conversion rate and minimization of production of unreacted materials and reaction by-products may be provided. In addition, the present invention implements a high conversion rate and a high selectivity even by a simplified process configuration, and thus may be usefully utilized in an economical method of preparing laurolactam, allowing commercially easy mass production.