A substrate for mounting a semiconductor chip is formed as a multilayer substrate by alternately laminating insulation layers and wiring layers. Wires of the wiring layers are electrically connected through a via-hole for interlayer continuity. A through-hole provided through the insulation layer of the outermost surface layer is formed. A bump is inserted in the through-hole to a bump allocating position of the semiconductor chip to be mounted in the insulation layer of the outermost surface layer. A portion of the wire in the wiring layer of the outermost surface layer is projected to the internal side of through-hole at the aperture of the through-hole.