Provided are a substrate processing apparatus and a method of manufacturing a semiconductor device using the same. The substrate processing apparatus includes a lower electrode assembly, an upper electrode assembly disposed on the lower electrode assembly, and a plasma processing region between the lower electrode assembly and the upper electrode assembly. The lower electrode assembly includes a substrate support supporting a substrate, a coupling ring assembly surrounding the substrate support, an edge ring on the coupling ring assembly, and at least one upper contact pad contacting a lower surface of the edge ring and contacting at least one of the substrate support and the coupling ring assembly, the at least one upper contact pad being conductive. The coupling ring assembly includes a coupling ring and a conductive side contact pad in contact with a side surface of the substrate support and an inner surface of the coupling ring.