To provide a method of producing an adamantane skeleton-having epoxy compound useful as a raw material for a sealant used when sealing a near-ultraviolet LED and a white LED, whereby a product with high purity can be obtained at a high yield in a short time in comparison with a previous method.

The epoxy compound having an adamantane skeleton such as 1,3-bis(glycidyloxy) adamantane is obtained by epoxydation by reacting, for example, an allyloxy compound having an adamantane skeleton such as 1,3-bis(allyloxy) adamantane, a nitrile compound such as benzonitrile and aqueous hydrogen peroxide in the presence of a basic compound such as potassium carbonate.