After a measurement apparatus records a magnetization state of a reference pattern on at least one specific track of a recording medium, it generates a leakage magnetic field of a demagnetization pattern and demagnetizes the magnetization state of the reference pattern using the leakage magnetic field. Then, the measurement apparatus calculates a difference between the read output of a reference pattern before demagnetization and the read output of a reference pattern after demagnetization on the specific track and obtains a leakage magnetic field of a recording head from the obtained difference.