According to a conventional method for producing an olefin oxide, hydrogen peroxide and an olefin oxide as a product are obtained in the state of a mixture, and in order to decrease the content of hydrogen peroxide in the mixture, it is necessary to distill the mixture to separate hydrogen peroxide from the olefin oxide. The present invention provides a method for producing an olefin oxide including a reaction step of reacting hydrogen peroxide with an olefin in the presence of a solvent and a titanium silicate catalyst; and a step of mixing a reducing agent containing at least one selected from the group consisting of a sulfide and hydrazine with the reaction solution obtained in the reaction step.