Disclosed is a non-halogen type highly heat resistant flame retardant epoxy resin composition that is made by compounding a phosphorous-modified epoxy resin with a phosphazene compound as a flame retardant additive, wherein the phosphorous-modified epoxy resin is obtained by reacting a phosphorous-containing compound with an epoxy resin. The non-halogen flame retardant and highly heat resistant phosphorous-modified epoxy resins according to the present invention have the excellent flame retardancy property and the good thermal property without halogen and thus can be advantageously utilized in manufacturing a printed circuit board (PCB) and for complex materials.