A pedestrian airbag system according to the present invention is mounted to a rear portion of a sheet metal hood panel of a vehicle. The airbag system includes an airbag inflated so as to cover an area from the rear portion of the hood panel to a front side of a front pillar by being supplied with inflation gas; a case for accommodating the airbag, and an airbag cover formed of synthetic resin and which covers the upper side of the folded airbag so as to allow projection of the airbag when inflated. The air bag cover is disposed at the rear portion of the hood panel so that the upper surface of the airbag cover is continuous with the upper surface of the hood panel on the front portion, elongated in the direction of the width of the hood panel, and mounted to the hood panel so as to be capable of moving in the direction of the width of the hood panel. According to the pedestrian airbag system of the invention, deterioration of the appearance of the airbag cover due to thermal expansion can be prevented.