Abstract: The present invention relates to a phenolic hydroxy group-containing rubber-modified polyamide resin which has, in the molecule, a phenolic hydroxy group-containing aromatic polyamide segment having a structure represented by the following formula (A) (wherein, m and n are average values and Ar represents a divalent aromatic group) and a butadiene (co)polymer segment selected from the following formula (B-1) or (B-2), —(CH2—CH?CH—CH2)X—??(B-1) —(CH2—CH?CH—CH2)Y—(CH2—CH(CN))Z—??(B-2) (wherein, each of x, y and z is an average value and 0.01?z/(y+z)?0.13, x represents a positive number of 5 to 200, and also y+z is a positive number of 10 to 200), and a resin composition containing said resin, in particular an epoxy resin composition; a cured product of said epoxy resin composition is excellent in flexibility, heat resistance and electrical properties especially at high temperature and high humidity.