A creasing and folding machine, comprising: a creasing mechanism for forming a plurality of creases on a sheet; a folding mechanism for receiving the sheet from the creasing mechanism and folding the sheet along the creases; and a controller for controlling operations of the creasing mechanism and the folding mechanism; wherein the creasing mechanism comprises: a conveying roller (10,11) for conveying the sheet; and a creasing section for creasing the sheet which is delivered from the conveying roller (10,11); wherein the folding mechanism comprises: a plurality of folding knives for pressing the sheet along the creases at edges of the folding knives; and a plurality of pairs of folding rollers each of which is composed of two folding rollers disposed opposite to each other with a gap therebetween, the gaps being opposite to the edges of the folding knives; wherein the sheet is pressed by the folding knives so as to be inserted into the gaps and folded along the creases; characterized in that the creasing section comprises: first and second creasing units (4,5) aligned in a conveying direction (F, F') of the sheet; wherein the first creasing unit comprises: a first convex block opposite to a first surface of the sheet; and a first concave block opposite to a second surf ace of the sheet, the first convex and concave blocks being moved toward each other so as to form a first crease of the creases which provides a recess on the first surface of the sheet and a protrusion on the second surface of the sheet; and wherein the second creasing unit comprises: a second concave block opposite to the first surface of the sheet; and a second convex block opposite to the second surface of the sheet, the second concave and convex blocks being moved toward each other so as to form a second crease of the creases which provides a protrusion on the first surface of the sheet and a recess on the second surface of the sheet. a creasing mechanism for forming a plurality of creases on a sheet; a folding mechanism for receiving the sheet from the creasing mechanism and folding the sheet along the creases; and a controller for controlling operations of the creasing mechanism and the folding mechanism; wherein the creasing mechanism comprises: a conveying roller (10,11) for conveying the sheet; and a creasing section for creasing the sheet which is delivered from the conveying roller (10,11); wherein a conveying roller (10,11) for conveying the sheet; and a creasing section for creasing the sheet which is delivered from the conveying roller (10,11); wherein the folding mechanism comprises: a plurality of folding knives for pressing the sheet along the creases at edges of the folding knives; and a plurality of pairs of folding rollers each of which is composed of two folding rollers disposed opposite to each other with a gap therebetween, the gaps being opposite to the edges of the folding knives; wherein a plurality of folding knives for pressing the sheet along the creases at edges of the folding knives; and a plurality of pairs of folding rollers each of which is composed of two folding rollers disposed opposite to each other with a gap therebetween, the gaps being opposite to the edges of the folding knives; wherein the sheet is pressed by the folding knives so as to be inserted into the gaps and folded along the creases; characterized in that the creasing section comprises: first and second creasing units (4,5) aligned in a conveying direction (F, F') of the sheet; wherein first and second creasing units (4,5) aligned in a conveying direction (F, F') of the sheet; wherein the first creasing unit comprises: a first convex block opposite to a first surface of the sheet; and a first concave block opposite to a second surf ace of the sheet, the first convex and concave blocks being moved toward each other so as to form a first crease of the creases which provides a recess on the first surface of the sheet and a protrusion on the second surface of the sheet; and wherein a first convex block opposite to a first surface of the sheet; and a first concave block opposite to a second surf ace of the sheet, the first convex and concave blocks being moved toward each other so as to form a first crease of the creases which provides a recess on the first surface of the sheet and a protrusion on the second surface of the sheet; and wherein the second creasing unit comprises: a second concave block opposite to the first surface of the sheet; and a second convex block opposite to the second surface of the sheet, the second concave and convex blocks being moved toward each other so as to form a second crease of the creases which provides a protrusion on the first surface of the sheet and a recess on the second surface of the sheet. a second concave block opposite to the first surface of the sheet; and a second convex block opposite to the second surface of the sheet, the second concave and convex blocks being moved toward each other so as to form a second crease of the creases which provides a protrusion on the first surface of the sheet and a recess on the second surface of the sheet.