A scoring machine incorporated in a sheet folding apparatus forms scores on sheets according to a folding pattern. The scoring machine comprises upper and lower rotary shafts provided with pairs of convex and concave rollers, and a positioning unit slidably attached to a slide guide. When a rotatable member is arranged at a standing position, the convex roller engages with a groove on one end face of the rotatable member, or the concave roller engages with a projection on the other end face of the rotatable member. A sequence pattern of the pairs of convex and concave rollers on the upper and lower rotary shafts corresponding to the folding pattern is displayed on a display. The positioning unit stops at the specified positions of the pairs of convex and concave rollers while sliding.