Abstract: A folder includes a board with one or more folding marks provided at the central position. The folding mark can separate the board into two folding panel boards. And, a folder body is provided at the inner face of a panel board adjacent to the folding mark, where a folder will take shape to hold the documents. The board is made of multi-layered sheets, with its middle layer including one or more foamed plastic layers. And, two plastic surface layers are attached to the surfaces of both sides of the middle layer. Thereupon, it is possible to enhance the ruggedness of the folder 20, reduce the manufacturing cost and offer more chromatism and diversity.