A magnetic sensor comprises a thin-film-like magnetic tunnel effect element (magnetoresistive effect element) 11. A coil 21 is disposed in a plane under the magnetic tunnel effect element 11 and parallel to a thin-planar film surface of the element. The coil 21 is a double spiral type coil which includes a first spiral conductor portion 21-1 and a second spiral conductor portion 21-2. The magnetic tunnel effect element 11 is disposed between a spiral center P1 of the first conductor portion 21-1 and a spiral center P2 of the second conductor portion 21-2 in a plan view. The first and second conductor portions 21-1 and 21-2 are connected such that electric currents in the same direction pass through a part of the first conductor portion 21-1 that overlaps the magnetic tunnel effect element 11 in a plan view and through a part of the second conductor portion 21-2 that overlaps the magnetic tunnel effect element 11 in a plan view.