A method is for producing propylene oxide, the method including the steps of: reacting hydrogen peroxide with propylene either in an acetonitrile solvent or in a mixture of solvents which include acetonitrile and water, in presence of a titanosilicate catalyst, whereby a reaction mixture containing propylene oxide is obtained; separating the reaction mixture obtained in the reacting into a gas and a reaction liquid; and distilling the reaction liquid obtained in the separating, whereby the reaction liquid is separated into a column top liquid containing propylene oxide, and a column bottom liquid including acetonitrile or a combination of acetonitrile and water, in combination with other steps. This enables industrially efficient production of propylene oxide with use of acetonitrile.