To provide a method for producing propylene oxide by which whole volume of a reactor of an epoxidation step can effectively be utilized and a reaction proceeds efficiently and the deterioration of a catalyst caused by locally accumulating the heat of the reaction can be prevented and by-products can be suppressed.

This method for producing propylene oxide comprises a step for obtaining propylene oxide and cumyl alcohol by reacting cumene solution containing cumene hydroperoxide and an excess amount of propylene in a liquid phase in the presence of a solid catalyst and a step for separating and recovering unreacted propylene contained in the reaction solution of the epoxidation step and recycling the recovered propylene to the epoxidation step as a raw material for epoxidation step. In the method, the total concentration of carbon monoxide and oxygen in propylene recycled from the propylene recovery step to the epoxidation step is kept to ≤10 wt.%.