To provide a blade hardly deflecting and superior in the flexural rigidity by applying the specific reinforcement means to the blade.

A knife-edge 11 is extended between the edges of the side surfaces 9 at both sides in the thickness direction A of a blade body 6. A reinforcement part 13 swelled in the thickness direction by the plastic working is integrally formed on one side surface 9. The swelled reinforcement part 13 comprises a projecting surface 13a welled at one of the side surfaces 9 side, and a recessed surface 13b corresponding to the convex surface 13a at the other side surface 9 side. The swelled reinforcement part 13 is integrally formed along a back edge 12 in the neighborhood of the back edge 12 at a side opposite to the knife-edge 11, and in the neighborhood of a holder support hole 10 formed between both side surfaces 9 of the blade body 6. Whereby the blade body is totally hardly bent and its flexural rigidity can be improved by the function of the swelled reinforcement part 13. The cutting by the knife-edge 11 can be smoothly performed regardless of the formation of the projecting surface 13a of the swelled reinforcement part 13.