A semiconductor device includes a power module, a circuit package, and a joint portion joining the power module and the circuit package. The circuit package includes a semiconductor element, a wiring layer electrically connected with the semiconductor element, a heat conductive member, and a second mold resin portion sealing the semiconductor element and the heat conductive member. The wiring layer includes a connecting portion connected with the heat conductive member. One of the connecting portion or the heat conductive member is joined with a signal wire in the power module via the joint portion. The heat conductive member penetrates the second mold resin portion in a thickness direction of the semiconductor element. The heat conductive member and the connecting portion are arranged in a straight line in the thickness direction of the semiconductor element.