The present invention provides a method for producing an epoxy compound by a reaction of an olefin compound with hydrogen peroxide, wherein the epoxy compound is stably and safely produced using a hydrogen peroxide stabilizer for reducing an oxygen gas generated from hydrogen peroxide. A method for producing an epoxy compound by a reaction of an olefin compound with hydrogen peroxide, wherein the reaction is carried out in the presence of an organophosphorus compound in such a reaction medium that the pH is maintained within a range of more than 7.5 and less than 12.0. The olefin compound may be 1,3,5-tris-(alkenyl)-isocyanurate. The alkenyl group in the olefin compound may be 3-butenyl group, 4-pentenyl group, 5-hexenyl group, 6-heptenyl group, or 7-octenyl group. The epoxy compound may be 1,3,5-tris-(epoxyalkyl)-isocyanurate. The reaction medium may be such a reaction medium that the pH is maintained within a range of 8.0 to 10.5.