An object of the present disclosure is to provide a semiconductor device capable of confirming withstand voltage of a snubber circuit after providing the snubber circuit and a method of manufacturing the semiconductor device. A semiconductor device according to the present disclosure includes: an insulating substrate; a circuit patterns provided on the insulating substrate; a snubber circuit substrate provided on the insulating substrate separately from the circuit patterns; a resistance provided on one of the circuit patterns and the snubber circuit substrate; a capacitor provided on another one of the circuit patterns and the snubber circuit substrate; and at least one semiconductor element electrically connected to the resistance and the capacitor.