Abstract: A method of manufacturing a cushion material by applying high frequency welding to a sandwich consisting of a core layer of foamed material, a surface material layer and a backing material layer, in which a fine powdery welding material is previously injected or impregnated in desired weld areas of the foamed material layer. The method comprises floating the fine powdery welding material in the form of a cloud, and blowing up the fine powdery welding material floating in cloud-like form to impregnate the desired areas of the foamed material layer with the fine powdery welding material.