A rotary head apparatus includes a rotary drum having two magnetic heads mounted
thereon. Each magnetic head has a recording-medium opposing surface curved in two
convex shapes extending towards the outside of the drum, one along the longitudinal
cross section of the magnetic head extending across the centerline laterally dividing
the magnetic head into two parts so as to be orthogonal to the sliding direction
of the recording medium, and the other along the lateral cross section orthogonal
to the centerline. The apex of the lateral cross section is gradually displaced
from the centerline as distancing itself from the center of the surface in the
longitudinal direction and in the opposite direction to the above displacement
as distancing itself from the center in the reverse longitudinal direction. Each
displacement of the apex laterally away from the centerline in a sliding area of
the recording medium is at most 2 m.
