An electronic component built-in multi-layer wiring board that comprises collectively stacked therein a plurality of first printed wiring boards by thermal compression bonding, and that comprises an electronic component package built in thereto, wherein the electronic component package comprises a first electronic component built in thereto and a plurality of second printed wiring boards stacked to have electrodes on an outermost surface of the package at a pitch that is wider than the electrode pitch of the first electronic component and that is matched to the wiring pitch of the first printed wiring boards, the electronic component built-in multi-layer wiring board includes a second electronic component having a thickness which is greater than that of the first electronic component, and the electronic component package having a thickness which is 80% to 125% of the thickness of the second electronic component.