To neatly cut a rib with small power.

A rib cutter includes: a fulcrum member 4 coming into contact with one of side faces of a long rib 2a protruding from an object 2 whose rib is to be cut; a point-of-application member 7 coming into contact with the other side face of the rib 2a; and a rotary operating member 9 rotating the member 7 around the fulcrum member 4 brought into contact with the first side face of the rib 2a. The rotary operating member 9 is rotated while the members 4 and 7 are located across the rib 2a, and then the rib 2a is cut by couple of forces of the members 4 and 7. The point-of-application member 7 comprises a biting edge 7A biting the second side face of the rib 2a by the rotation of the member 9. The biting edge 7A is formed to be elongate in the longitudinal direction of the rib, and a part first coming into contact with the second side face of the rib by the rotation of the member 9 is formed at an tip of the edge 7Aa far from the fulcrum member 4. The tip of the edge 7Aa is shaped to be sharp.