A semiconductor module according to one embodiment includes a circuit substrate and first and second transistors for upper and lower arms of a power conversion circuit. The circuit substrate includes a substrate having first and second insulating parts and a conductive layer disposed therebetween, first and second input interconnection patterns coupled to the first and second input terminals, and an output interconnection pattern coupled to an output terminal. The first and second transistors are electrically coupled to the first and second input terminals through the first and second input interconnection patterns, respectively. The conductive layer has a first area situated opposite the first input interconnection pattern and a second area electrically coupled to the first area. The second area is electrically coupled to the second input interconnection pattern. The conductive layer is insulated from the first input interconnection pattern and the output interconnection pattern by the second insulating part.