Abstract: The present invention provides an apparatus for producing an epoxy compound derived from an olefin by causing a reaction of hydrogen, oxygen, and the olefin in a liquid solvent in the presence of a catalyst in a reactor, wherein a vapor phase in the reactor contains an inert gas; hydrogen, an oxygen-containing gas with an oxygen concentration of at least 90% by volume, and the olefin are supplied to the vapor phase and/or liquid phase of the reactor to cause a reaction; and there exist a means for taking out the liquid phase containing the reaction product from the reactor.