A semiconductor device includes a substrate having a front surface and a mounting surface that are separate from each other in a thickness direction. The substrate is formed with a through-hole that penetrates through in the thickness direction. A semiconductor element is mounted on the front surface of the substrate, and a front-surface wire line is formed on the front surface of the substrate to be electrically connected to the semiconductor element. A column is provided inside the through-hole, and is electrically connected to the front-surface wiring line. An electrode pad is provided on the mounting surface of the substrate, and is electrically connected to the column. A resin-layer through portion is also provided inside the through-hole. The semiconductor element is covered with a sealing resin. The resin-layer through portion has an orthogonal surface in contact with the column. The orthogonal surface is orthogonal to the mounting surface.