The influence of the recording field direction on the linearity of the transition is investigated when a signal is recorded on hard disks whose recording layers have the stacked structure. It is found that the linearity of the transition increases with increase of the ratio of the in-plane component of the recording field to the perpendicular one, and the recording field direction dependence of the transition linearity is tolerant to the variation of the recording layer structure. It is inferred that the magnetization distribution in the transition area reflects the demagnetized domain structure, that is to say, the linearity of the transition increases since the magnetization of both upper and lower layers gets to be reversed separately with increase of the ratio of the in-plane component of the recording field to the perpendicular one.