Magnet evaluation device and method

A magnet evaluation method for evaluating a magnet having at least two magnetic pieces bonded to an insulating material sandwiched between two adjacent ones of the magnetic pieces, the magnet evaluation method comprising:

• generating a magnetic field with an excitation coil such that a magnetic field is produced having a size in a range that corresponds to a region including the insulating material;
• detecting an eddy current amount in the magnet using a detection coil that has a coil diameter that is smaller than a length of one of the magnetic pieces in a direction in which the magnetic pieces are aligned, the detection coil being coaxial with the excitation coil;
• and
• evaluating the magnet by applying a magnetic field generated by the excitation coil to the magnet and determining the magnet to be defective upon detection of the eddy current amount by the detection coil exceeding a preset threshold value for an eddy current amount in which the preset threshold value is obtained in advance from a relationship between an eddy current that is generated in the magnet and a generated heat amount.