In a composite sheet manufacturing device, a second roller having a plurality of first projections and a third roller are disposed so as to be adjacent to a first roller having multiple recessed areas. The outer diameters of the first and third rollers are the same size. The third roller is joined to the first roller with a first gear pair therebetween, so as to rotate at the same rotation frequency as that of the first roller. A first sheet that is fed in between the first roller and the second roller is shaped by being pushed into the recessed areas of the first roller by the first projections of the second roller. A second sheet is then superimposed onto the first sheet and is passed through the space between the first roller and the third roller, and the first and second sheets are thereby bonded to each other.