To provide an integrated floor-raising material/duct capable of securing sufficient rigidity while achieving weight reduction.

The integrated floor-raising material/duct, which has a peripheral sidewall between an upper sidewall 12 and a back sidewall 14 and of which height of the peripheral sidewall is used to raise a floor, is of an integrated hollow double wall structure formed by the blow molding. A duct part, which forms an air flow passage inside by the upper sidewall 12 and the back sidewall 14, and hollow parts, which are structured with the other sidewall facing a first long groove 23 or a second long groove 24, the upper sidewall 12, the back sidewall 14, and the peripheral sidewall, are formed in such a way as to be partitioned from each other. On edge parts along the first long groove 23 or the second long groove 24 of the upper sidewall 12 or the back sidewall 14 of the hollow part, a plurality of reinforcing ribs, which are of a groove shape each projecting inward from the upper sidewall 12 or the back sidewall 14 and on which opening are formed so as to face the first long groove 23 or the second long groove 24, are provided with predetermined intervals.