A semiconductor device includes a first wiring substrate having a first surface and a second surface opposite to the first surface, and including a plurality of first electrode pads on the first surface, and a second wiring substrate having a third surface facing the first surface and a fourth surface opposite to the third surface, and including a plurality of second electrode pads on the third surface. A plurality of first semiconductor chips are stacked between the first surface and the third surface. A first columnar electrode extends in an oblique direction with respect to a first direction substantially perpendicular to the first surface and the third surface, and connects between the plurality of first electrode pads and the plurality of second electrode pads. A first resin layer covers the plurality of first semiconductor chips and the first columnar electrode between the first surface and the third surface.