An image taking device has a multifocal lens which changes its focal
length to change the image taking area on a subject from which an image
is to be taken by an image pickup sensor, a distance sensor for measuring
the distance to the subject, an image taking distance buffer unit for
temporarily storing the image taking distance measured at a past time, a
focal length computation unit which computes the focal length of the
multifocal lens on the basis of the image taking distance at the present
time measured by the distance sensor and the image taking distance
supplied from the mage taking distance buffer unit, and a focus control
unit which controls the focal length of the multifocal lens so that the
focal length of the multifocal lens equals the focal length computed by
the focal length computation unit.