Provided are an epoxy resin, a polyvalent hydroxy resin and a composition thereof which have excellent curability, which provide cured products with excellent mechanical strength, flame resistance, humidity resistance, low elasticity, etc., and which are suitable for applications such as encapsulation of electronic components, circuit board material, etc. This polyvalent hydroxy resin is an aralkyl denatured polyvalent hydroxy resin which is obtained by reacting a narrow disperse polyvalent hydroxy compound with an aralkylating agent of styrenes, etc., the narrow disperse polyvalent hydroxy compound comprising 15% or less of n=1 component, and 50% or more of a total of n=2 and n=3 components, and having Mw/Mn of 1.2 or less. In addition, the present invention is an epoxy resin obtained by reacting the aralkyl denatured polyvalent hydroxy resin with epichlorohydrin. Furthermore, the present invention is an epoxy resin composition which contains, as an essential component, the aralkyl denatured polyvalent hydro
