The present invention provides a resin composition which is capable of forming a roughened surface with low roughness on a surface of an insulating layer regardless of roughening conditions when used as a material of an insulating layer of a printed wiring board, and is excellent in adhesion between the insulating layer and a plated conductor layer, and also which has low thermal expansion coefficient (linear expansion coefficient) and high glass transition temperature and is also excellent in moist heat resistance. Disclosed is a resin composition including an epoxy compound (A), a cyanate ester compound (B) and an inorganic filler (C), wherein the cyanate ester compound (B) is at least one selected from the group consisting of a naphthol aralkyl type cyanate ester compound, an aromatic hydrocarbon formaldehyde type cyanate ester compound, a biphenyl aralkyl type cyanate ester compound and a novolak type cyanate ester compound; and the content of the epoxy compound (A) is 60 to 75% by weight based on the tot
