According to one embodiment, there is to provide a data write method which is applied to a disk drive, for recording data on a disk medium by a head mounted on a rotary type actuator. The method carries out a track pitch conversion processing so that a track pitch of data track is set larger than a track pitch in an intermediate circumferential area based on an azimuth angle of the head in the case where the position of the data track is included in an inner circumferential area or outer circumferential area on the disk medium.