To provide a DC bias current control circuit which can be disposed in an identical chip to a superconductive circuit requiring a DC bias current, or in the vicinity of an identical temperature to the superconductive circuit requiring the DC bias current, and can be intended to precisely control to an optimum value of the DC bias current, and simplify a system containing the superconductive circuit.

There are provided a feedback loop 25 which is coupled in a magnetic field to a DC bias current line 12 for supplying a DC bias current IB to a superconductive circuit 10, and a feedback loop control circuit (a superconductive coil 14, a DROS 15, an inductor 23, a resistor 24, and inductors 33, 34) for detecting the DC bias current IB to supply a single flux quantum required for cancelling a change component from the optimum value of the DC bias current IB to the feedback loop 25.