PURPOSE: To obtain a small-sized circuit and to prevent malfunction due to a magnetic flux trap by forming the circuit only by a resistor and Josephson junction.

CONSTITUTION: A Josephson (J) junction 20 and a resistor 25 are connected to a gate current supplying line 32 in parallel, a J circuit 22 is connected to the J junction 20 in series and a data input line 35 is connected to the input terminal of the J circuit 22. A J circuit 23 is connected to a gate current supplying line 33 and a data output line 36 is connected to the output terminal of the J circuit 23. A J circuit 24, a resistor 29 and a J junction 21 are connected to a current supplying line 34 in series and a resistor 28 is connected to the output terminal of the J circuit 24. A data output line 37 is connected to a connection poing between the resistor 29 and the J junction 21 and the output terminal of the J circuit 22 is connected to the input terminals of the J circuits 23, 24 in parallel. Since the titled circuit is formed only by the resistor and Josephson junction the circuit reduces the size and the malfunction due to the magnetic flux trap is prevented.