A superconducting complex quantum computing circuit comprising: a circuit substrate in which a wiring pattern of a circuit element is formed, which includes a plurality of quantum bits and a plurality of measurement electrodes for observing a state of the quantum bit, and a plurality of ground patterns which are at a ground potential are formed on a substrate surface, and that includes a plurality of through-substrate electrodes which connect the ground pattern formed on a first surface (S 1) of the substrate surface and the ground pattern formed on a second surface, which is a surface opposite the first surface, inside the substrate; a first ground electrode that includes a first contact portion which is in contact with the ground pattern formed on the first surface of the circuit substrate, and a first non-contact portion which has a shape corresponding to a shape of the wiring pattern formed on the first surface; a second ground electrode that includes a second contact portion which is in contact with the ground pattern formed on the second surface of the circuit substrate; a plurality of control signal lines that are provided with a tip and a contact spring pin at each tip, the contact spring pin being in contact with a position corresponding to the quantum bit to press the first surface of the circuit substrate against the first ground electrode or to press the second surface of the circuit substrate against the second ground electrode; and a pressing member that presses the first ground electrode against the first surface of the circuit substrate or presses the second ground electrode against the second surface of the circuit substrate, wherein the first ground electrode is in contact with the ground pattern via a first extension portion formed by a superconducting material having an extensibility higher than an extensibility of the ground pattern, and the second ground electrode is in contact with the ground pattern via a second extension portion formed by the superconducting material having extensibility higher than the extensibility of the ground pattern, wherein extensibility is a property of malleability or ductility, or both malleability and ductility. a circuit substrate in which a wiring pattern of a circuit element is formed, which includes a plurality of quantum bits and a plurality of measurement electrodes for observing a state of the quantum bit, and a plurality of ground patterns which are at a ground potential are formed on a substrate surface, and that includes a plurality of through-substrate electrodes which connect the ground pattern formed on a first surface (S 1) of the substrate surface and the ground pattern formed on a second surface, which is a surface opposite the first surface, inside the substrate; a first ground electrode that includes a first contact portion which is in contact with the ground pattern formed on the first surface of the circuit substrate, and a first non-contact portion which has a shape corresponding to a shape of the wiring pattern formed on the first surface; a second ground electrode that includes a second contact portion which is in contact with the ground pattern formed on the second surface of the circuit substrate; a plurality of control signal lines that are provided with a tip and a contact spring pin at each tip, the contact spring pin being in contact with a position corresponding to the quantum bit to press the first surface of the circuit substrate against the first ground electrode or to press the second surface of the circuit substrate against the second ground electrode; and a pressing member that presses the first ground electrode against the first surface of the circuit substrate or presses the second ground electrode against the second surface of the circuit substrate, wherein the first ground electrode is in contact with the ground pattern via a first extension portion formed by a superconducting material having an extensibility higher than an extensibility of the ground pattern, and the second ground electrode is in contact with the ground pattern via a second extension portion formed by the superconducting material having extensibility higher than the extensibility of the ground pattern, wherein extensibility is a property of malleability or ductility, or both malleability and ductility.