A superconducting circuit device of a
voltage-type logic device is large in current driving capability and, accordingly,
electric power consumption; however, the switching speed is not so fast, and a superconducting circuit device of a fluxoid-type logic device is small in current driving capability and, accordingly, the
electric power consumption; however the switching speed is faster than that of the superconducting circuit device of the
voltage-type logic device, wherein the superconducting circuit device of the
voltage-type logic device and the superconducting circuit device of the fluxoid-type logic device are selectively used in a superconducting circuit such as a superconducting
random access memory, a superconducting NOR circuit and a superconducting
signal converting circuit so as to realize small
electric power consumption and high-speed switching action.