Knife-type folding machine

A conveying unit 2including conveyor belts 7, a stopper 3positioning a sheet S at a folding position P on a conveying path 2, a knife-type folding unit 4, an anti-bounce roller unit 16having rollers 25a, 25b, and a motor 22 are provided. The rollers can be moved back and forth. A roller rotational speed monitoring unit 31 and a roller position setting unit 32 operatively connected to the motor are further provided. In setting mode, the rollers are moved from an upstream or a downstream of a tail end of the sheet positioned at the folding position P toward the tail end at a constant speed and stopped when the rotational speed of the rollers changes.