A focusing controlling device is for a camera having a photographing lens
and an imaging surface. The focusing controlling device includes a focus
adjuster that adjusts a focus position of the photographing lens based on
field curvature data. The field curvature data indicates a field
curvature ratio which is a ratio of a distance between an image point of
light transmitted through the photographing lens and the imaging surface
to a focal distance of the photographing lens, the field curvature data
being set for a partial area of the imaging surface as an average value
of the field curvature ratios for the partial area.