To provide a method for producing purified propylene oxide, by which reaction heat generated in a process for reacting cumene hydroperxide with propylene in the presence of an epoxidation catalyst to obtain the propylene oxide and the cumyl alcohol is effectively utilized to totally improve the utilization efficiency of heat in the system.

The reaction heat generated in the following first process is used as a heat source for the rectification of the third process and/or as a beat source for the rectification of the fourth process. The first process: a process for reacting the cumene hydroperxide with the propylene in the presence of the epoxidation catalyst to obtain the propylene oxide and the cumyl alcohol. The third process: a process for rectifying the fraction (2) to obtain a fraction (4) containing crude propylene oxide and a fraction (6) containing the cumyl alcohol. The fourth process: a process for rectifying the fraction (4) to obtain a fraction (7) containing the pure propylene oxide.