Disclosed is an alicyclic diepoxy compound which gives a cured article suffering from no deterioration in properties even when used in hot and humid surroundings or used under such conditions as to give a strong acid, which is highly reactive upon curing, and which gives a cured article superior typically in thermal stability. Specifically, the alicyclic diepoxy compound includes a 3,4,3′,4′-diepoxybicyclohexyl compound represented by following Formula (1): wherein R1 to R18 each represent a hydrogen atom, a halogen atom, a hydrocarbon group which may have an oxygen atom or a halogen atom, or a substituted or unsubstituted alkoxy group, in which the alicyclic diepoxy compound contains isomers of the 3,4,3′,4′-diepoxybicyclohexyl compound in a content of less than 20% based on the total of the 3,4,3′,4′-diepoxybicyclohexyl compound and the isomers thereof in terms of peak area ratio as determined by gas chromatography.