To form fluff of fiber on both surfaces of a fiber product, by giving half-cut from both surfaces of the fiber product.

While abutting peripheral surfaces 24a, 24a of a first roll 20 are press-contacted on an outer peripheral surface 32a of a second roll 30, a blade tip 42a of a first cutting edge 42 and a receiving surface 52a of a second receiving portion 52 oppose to each other with keeping a clearance, and a blade tip 53a of a second cutting edge 53 and a receiving surface 43a of a first receiving portion 43 also oppose to each other with keeping a clearance. If work WA is clipped by a first rib 41 and a second rib 51, fiber bundle layers Wb, Wb provided on back and front surfaces of a base material sheet Wa are respectively cut by the cutting edges 42, 53. The fiber bundle layer Wb fluffs at a cut portion, so that dust collecting effect comes into play.