1. A driver certifying system, comprising: an iris pattern acquiring means for acquiring iris pattern of a driver who sits on a driver's seat of a vehicle; a driver certifying means for certifying whether or not the driver is an authentic driver by comparing the iris pattern with registered iris pattern of the authentic driver; and a function activating means for activating at least one function of the vehicle, when the driver is certified as the authentic driver, wherein said iris pattern acquiring means is arranged in the ceiling of the vehicle.