A novolac epoxy compound having an alkoxysilyl group of which composite has low CTE and increase of glass transition temperature, and requiring no coupling agent, a production method thereof, an epoxy composition including the same and a cured article thereof, are provided. A novolac epoxy compound having an alkoxysilyl group of Formulae I-1 to I-4, a production method of the novolac epoxy compound having an alkoxysilyl group by the epoxidation, alkenylation and alkoxysilylation of a novolac epoxy compound, a production method of the novolac epoxy compound having an alkoxysilyl group by the epoxidation and alkoxysilylation of a novolac epoxy compound, an epoxy composition including the novolac epoxy compound having an alkoxysilyl group, and a cured article, are provided. The cured article, i.e., the composite of the epoxy composition has improved chemical bonding efficiency due to alkoxysilyl groups. Low CTE and high glass transition temperature are exhibited.