Patent ID: 7079340

Claim:
A measurement apparatus for measuring a leakage magnetic field of a recording head, comprising: a recording head drive device for, after driving the recording head using a write electric current and recording a magnetization state of a reference pattern on at least one specific track of a recording medium, generating a leakage magnetic field of a demagnetization pattern by driving the recording head using a demagnetization electric current and for demagnetizing the magnetization state of the reference pattern using the leakage magnetic field; a read head drive device for driving a read head and generating a read output of a reference pattern before demagnetization and a read output of a reference pattern after demagnetization from the at least one specific track; a first storage device for storing the read output of the reference pattern before demagnetization together with track position information; a second storage device for storing the read output of the reference pattern after demagnetization together with track position information; and a magnetic field calculation device for calculating a difference between the read output of the reference pattern before demagnetization and the read output of the reference pattern after demagnetization and for obtaining the leakage magnetic field of the recording head from the obtained difference.