A hood structure comprises an outer and an inner which form a closed cross section through spaces. The inner's cross-sectional shape is an interconnected stair step curve based on a series of concentric geometric shapes. This multi-tiered hood structure can provide a uniform, excellent head impact resistance independent of material selection for the outer and inner panels. The multi-tiered hood structure also excels in rigidity, strength, weight, cost and manufacturability. Accordingly, the car body hood panel structure efficiently satisfies requirements of head impact resistance for pedestrian protection.