A semiconductor device includes a first substrate, a second substrate stacked over the first substrate, and a pillar member extending obliquely between the first and second substrates. The first substrate includes a mounting surface on which a semiconductor chip is mounted, with a resin interposed between the semiconductor chip and the mounting surface and extending beyond the periphery of the semiconductor chip on the mounting surface. The first substrate further includes a first pad forming part of the mounting surface and disposed outside the resin. The second substrate includes a second pad forming part of its surface facing toward the mounting surface. The second pad at least overlaps the resin when viewed in a direction in which the second substrate is stacked over the first substrate. The pillar member has first and second ends joined to the first and second pads, respectively, to electrically connect the first and second substrates.