To provide a demagnetization apparatus and method which can reduce the intensity of a magnetic field at a portion wherein a demagnetization coil is disposed without increasing the intensity of a magnetic field at a portion adjacent to the demagnetization coil.

The demagnetization apparatus 1 is disposed on the surface of a floor (structure) 7, and includes a magnetic field detecting means 9 for detecting the intensity and direction of a magnetic field on the surface of the floor, the demagnetization coil 2 disposed on the surface of the floor according to the detection results of the magnetic field detecting means, and a voltage applying means 3 for applying AC voltage whose amplitude is gradually alleviated over time to the demagnetization coil. The demagnetization apparatus 1 demagnetizes a magnetized portion inside the floor by a magnetic field generated by applying AC voltage to the demagnetization coil. The voltage applying means applies AC voltage to the demagnetization coil in such a manner that the direction of the magnetic field on the surface of the floor which is detected by the magnetic field detecting means and the direction of the magnetic field appearing on the surface of the floor in an initial stage of application of AC voltage to the demagnetization coil may be the same.