Provided is control relating to autofocusing in an image sensing apparatus having an image sensing unit for photoelectrically converting an optical image of a subject to obtain an image signal representing the subject, and an autofocus function, the apparatus being capable of performing photography using a fill-in light emission unit. Control includes setting a charge accumulation period of the image sensing unit, deciding light-emission time of the fill-in light emission unit based upon the charge accumulation period that has been set, performing control in such a manner that the fill-in light emission unit is caused to emit light for the decided light-emission time in sync with start of the charge accumulation period, and performing focusing control based upon the image signal obtained from the image sensing unit. Control of the fill-in light emission unit is executed repeatedly during control of focusing.