A method of manufacturing a component-built-in wiring substrate which exhibits excellent reliability, through improvement of adhesion between a resin filler and a core substrate, is provided. In some embodiments the method comprises a core substrate preparation step for preparing a core substrate, an accommodation-hole forming step for forming an accommodation hole in the core substrate, and a through-hole forming step for forming through-holes. In a plating-layer forming step, a plating layer is formed on an inner wall surface of the accommodation hole and plating layers are formed on the inner wall surfaces of the through-holes, which become through-hole conductors each having a hollow. In an accommodation step, a component is accommodated in the accommodation hole. In a resin charging step, a resin filler is filled into a gap between component side-surfaces and the inner wall surface of the accommodation hole and into the hollows.