Abstract: The present invention relates to a prepreg including an insulating resin composition impregnated into a substrate including a fibrous material and a porous support, and a printed circuit board including the same as an insulating layer. According to the present invention, it is possible to improve fire resistance, reduce weight, and reinforce mechanical characteristics by using a mixture of the fibrous material and the porous support as the substrate used for impregnation of the insulating resin composition and disposing the porous support around the fibrous material. Further, it is possible to reinforce local/overall strengths, facilitate manufacture of the product, increase resistance to bending stress, aseismatic, fireproof, and durable types, and secure improvement in a coefficient of thermal expansion by combining the porous support and a base resin and disposing the fibrous material in a main structural part which receives a force.