PURPOSE: To enhance sensitivity by reducing a diamagnetic field and a saturated magnetic field by constituting a main current passage of a plurality of ferromagnetic parts formed at a predetermined interval and a plurality of non-magnetic conductor parts connecting the same.

CONSTITUTION: Ferromagnetic membranes 12, 13 are formed on a glass substrate 11 and have a continuous fold-back pattern shape and are constituted of main current passage parts 14, 15 and bent parts 16, 17 and arranged so that the current directions thereof cross each other at a right angle. The passage parts 14, 15 consist of a plurality of ferromagnetic parts 14a, 15a formed into an almost square shape and non-magnetic conductor parts 14b, 15b electrically connecting the same respectively. One end parts of the passage parts 14, 15 are electrically connected to an output terminal 18 and power supply terminals 19 are respectively connected to the other end parts of said passage parts 14, 15. A voltmeter 35 is connected between the lead wire 33a from the terminal 19 and the terminal 18 through a lead wire 34. By the voltmeter 35, a change of voltage due to the sensed current changed by the anisotropic magnetic resistance effect of the membranes 12, 13 is detected.