PURPOSE: To dispense with wire bonding and prevent the occurrence of troubles caused by wire bonding by providing a SQUID on a board, and providing pads for directly making electrical connections to external circuits via lead wires at the peripheral edge section of the board.

CONSTITUTION: A SQUID 2, pads 3 for connecting lead wires, and a wiring pattern 4 connecting the SQUID 2 and the pads 3 are formed on a rectangular Si substrate 1 of a prescribed size. When this device is adapted to a SQUID fluxmeter, for example, not only a superconducting loop having Josephson junction but also a modulation coil feeding the compensating magnetic flux to the superconducting loop are integrally formed to compensate the change of the magnetic flux guided to the superconducting loop by an input coil guiding the external magnetic flux detected by a pickup coil to the superconducting loop.