To provide an epoxy resin composition which exhibits performance such as adhesion strength, independent of the curing temperature, without deteriorating the mechanical properties or heat resistancde which are inherent is the epoxy resin, and a preparation method therefor.

The epoxy resin composition contains an A-B type block copolymer comprising a polymer segment A formed out of (meth)acrylonitrile and a polymer segment B formed out of at least one (meth)acrylate ester represented by the formula (wherein, R1 is hydrogen or methyl group; R2 is an aliphatic hydrocarbon group). Preferably, the solubility parameter value of the polymer segment A, calculated from the Fedors equation, is 10 or larger and the glass transition temperature of the polymer segment B is 25°C or lower.