MAGNETIC BALANCE CURRENT SENSOR

To provide a current sensor that can be miniaturized, and that also has a high sensitivity. A magnetic-balance-system current sensor according to the present invention includes: a magnetoresistive element (141), a resistance value of the magnetoresistive element (141) being changed by application of an induction magnetic field generated by a measurement target current; magnetic cores (13) disposed in the vicinity of the magnetoresistive element (141); a feedback coil (12) disposed in the vicinity of the magnetoresistive element (141) and generating a cancelling magnetic field, the cancelling magnetic field being a field cancelling out the induction magnetic field; and a magnetic-field detecting bridge circuit (14) having two outputs having a voltage difference therebetween, the voltage difference being generated in accordance with the induction magnetic field. The measurement target current is measured on the basis of a current flowing through the feedback coil (12) when electricity is conducted through the feedback coil (12) due to the voltage difference and the induction magnetic field and the cancelling magnetic field enter a state of equilibrium in which the induction magnetic field and the cancelling magnetic field cancel each other out. The feedback coil (12), the magnetic cores (13), and the magnetic-field detecting bridge circuit (14) are formed on a same substrate.