A method for producing ethylene oxide, comprising: a step of supplying an ethylene oxide-containing reaction product gas produced in an ethylene oxidation reaction step in an ethylene oxidation reactor, in which ethylene is subjected to contact gas-phase oxidation using a molecular oxygen-containing gas in the presence of a silver catalyst, to an ethylene oxide absorption column to bring the reaction product gas into contact with an absorption liquid supplied to the ethylene oxide absorption column, supplying an ethylene oxide-containing column bottom liquid of the ethylene oxide absorption column to an ethylene oxide purification system, and purifying ethylene oxide in the ethylene oxide purification system; and a step of supplying at least part of a carbon dioxide gas-containing gas discharged from a column top part of the ethylene oxide absorption column to a carbon dioxide gas absorption column to bring the carbon dioxide gas-containing gas into contact with an absorption liquid, extracting the resulting carbon dioxide gas-rich absorption liquid as a column bottom liquid of the carbon dioxide gas absorption column and supplying the same to an upper part of a carbon dioxide gas stripper column, and stripping a carbon dioxide gas from the carbon dioxide gas-rich absorption liquid and discharging the same from a column top part of the carbon dioxide gas stripper column as an exhaust gas, wherein the concentration of molecular oxygen (O 2) in the molecular oxygen-containing gas supplied from outside the system into the system being 99.7% by volume or more, and wherein a raw material gas containing the ethylene is pressurized using a centrifugal compressor equipped with a dry gas sealing as a shaft sealing device, and the pressurized raw material gas is supplied to the ethylene oxidation reactor. a step of supplying an ethylene oxide-containing reaction product gas produced in an ethylene oxidation reaction step in an ethylene oxidation reactor, in which ethylene is subjected to contact gas-phase oxidation using a molecular oxygen-containing gas in the presence of a silver catalyst, to an ethylene oxide absorption column to bring the reaction product gas into contact with an absorption liquid supplied to the ethylene oxide absorption column, supplying an ethylene oxide-containing column bottom liquid of the ethylene oxide absorption column to an ethylene oxide purification system, and purifying ethylene oxide in the ethylene oxide purification system; and a step of supplying at least part of a carbon dioxide gas-containing gas discharged from a column top part of the ethylene oxide absorption column to a carbon dioxide gas absorption column to bring the carbon dioxide gas-containing gas into contact with an absorption liquid, extracting the resulting carbon dioxide gas-rich absorption liquid as a column bottom liquid of the carbon dioxide gas absorption column and supplying the same to an upper part of a carbon dioxide gas stripper column, and stripping a carbon dioxide gas from the carbon dioxide gas-rich absorption liquid and discharging the same from a column top part of the carbon dioxide gas stripper column as an exhaust gas, wherein the concentration of molecular oxygen (O 2) in the molecular oxygen-containing gas supplied from outside the system into the system being 99.7% by volume or more, and wherein a raw material gas containing the ethylene is pressurized using a centrifugal compressor equipped with a dry gas sealing as a shaft sealing device, and the pressurized raw material gas is supplied to the ethylene oxidation reactor.