A superconducting quantum interference device loop (2), a modulation coil (3) and an input coil (4) are formed in parallel and their axes being parallel to a substrate (1), on the substrate (1). At least one tap (4b) is formed at a predetermined position on the input coil (4). In a preferred embodiment, a superconductive shield (5) is formed on the substrate (1) in one body. The superconductive shield (5) surrounds the superconducting quantum interference device loop (2), the modulation coil (3) and the input coil (4).