A pedestrian airbag system for a vehicle includes an air bag housing installed under a rear portion of a hood panel of a vehicle, an inflator disposed in a center area within the air bag housing, and an air bag cushion having a pair of chambers. which are disposed at respective sides of the inflator within the airbag housing, connected to the inflator to be supplied with gas from the inflator, and inflated to eject from the hood panel when the inflator explodes, covering A-pillars respectively, which are disposed at respective sides in the widthwise direction of a vehicle body.