A semiconductor package includes an interposer having a separation layer on a rear surface of which a plurality of first recesses is arranged. A plurality of wiring structures is stacked on the separation layer alternately with a plurality of insulation interlayers. A plurality of semiconductor devices is arranged, side by side, on the interposer side and connected to a plurality of the wiring structures. A plurality of contact terminals on the rear surface of the separation layer is connected to the plurality of the wiring structures through the separation layer. A flatness deterioration of the interposer is minimized and the contact surface between the interposer and under fill resin is enlarged.