An object is to provide a technique capable of suppressing insulation defects caused by the arrival of bubbles contained in an adhesive at a circuit pattern in a semiconductor device. A semiconductor device includes the resin-insulated copper base plate having the copper base plate, the insulating layer provided on the upper surface of the copper base plate, and the circuit pattern provided on the upper surface of the insulating layer, the semiconductor element mounted on the upper surface of the resin-insulated copper base plate, the case joined to the outer peripheral portion of the resin-insulated copper base plate via the adhesive, the sealing material sealing, in the case, the upper surface of the resin-insulated copper base plate and the semiconductor element, and the roughening patterns formed on the upper surface of the insulating layer such that the circuit pattern is enclosed therewith in a plan view.