PURPOSE: To simplify fold making work by placing the edges of a vertical and a lateral allowance together on the external surface of a peripheral edge of an internal surface board, sewing the joint section, cutting off the sharp edge of an angular section obliquely, applying a coloring agent to the cut surface and pressing an uneven pattern on the section where the edges are placed together.

CONSTITUTION: The edges 7, 8 of a vertical allowance 2 and a lateral allowance 3 are allowed to attach to the external surface of a peripheral section of an interior surface board 5 in such a state that said edges 7, 8 are placed together on the external surface of a corner 9 of the board 5. This joint section is sewn with a string 10 to fix together an external surface board 4, a lining board 6, an internal surface board 5 and vertical and lateral allowances 2, 3. Next, the sharp edge of an angular section 12 formed by placing the edges together is cut obliquely, and at the same time, a coloring agent of the same color 14 as the external surface of the external surface board 4 is applied to the cut surface 13 so that it is less conspicuous. Furthermore, an uneven sector pattern 17 is embossed at the section where the edges are placed together of the angular section 12 using a separately prepared heated pressing trowel 16 with a flat branding mark 15 of an uneven equivalent part of a skeleton. Thus a trace of the section where the edges are placed together can be concealed and a notebook cover is completed.