To provide a multilayer wiring substrate which can prevent migration of copper between wiring traces to thereby realize a higher degree of integration, a solder resist layer 25 having a plurality of openings 35, 36 is disposed on a top surface 31 side, and IC-chip connection terminals 41 and capacitor connection terminals 42 are buried in an outermost resin insulation layer 23 in contact with the solder resist layer 25. Each of the IC-chip connection terminals 41 and the capacitor connection terminals 42 is composed of a copper layer 44 and a plating layer 46 covering the outer surface of the copper layer 44. A conductor layer 26 present at the interface between the solder resist layer 25 and the resin insulation layer 23 is composed of a copper layer 27 and a nickel plating layer 28 covering the outer surface of the copper layer 27.