The invention provides a semiconductor device which can reduce wiring crosstalk on a substrate. The semiconductor device is provided with an insulation substrate, first and second semiconductor chips, a plurality of connectors, external terminals, a plurality of jointing elements, a plurality of data signal wires, and a conductor layer. The insulation substrate is provided with first and second main surfaces. The first semiconductor chip is configured on the first main surface. The second semiconductor chip is configured on the first semiconductor chip, and controls the first semiconductor chip. The plurality of connectors are configured on the first main surface. The external terminals are configured on the second main surface. The plurality of data signal wires have one end connected to any one of the plurality of connectors, the other end connected to the first semiconductor chip or the external terminal, and middle parts adjacent in a specific area of the first main surface. The conductor layer covers the specific area at intervals, and has electrical conductivity and paramagnetism.