To provide a breaking device for injection needle capable of surely breaking injection needles supplied at random into many very small pieces without no constraints in supply attitudes of injection needles, simple in structure and excellent in breaking efficiency.

In each of a fixed blade block 3 and a movable blade block 4 arranged within a case, a plurality of recessed parts A and B in which holes are opened on an overlapped surface side, the bottom surfaces become inclined surfaces lowered toward the overlapped surface side and upper and lower edges of opened holes on the overlapped surface side become edges are provided in the vertical direction. The recessed part B of the fixed blade block 3 is divided into both sides by a partition wall 15 provided at the intermediate. Thickness of the partition wall 15 is set to be thicker, the lower the wall 15 is located. On an overlapped surface of projected blades 16 arranged in the vertical direction at positions between each of the upper and lower recessed part B on the overlapped surface of the fixed blade block 3 with the movable blade block 4 and the fixed blade block 3 of the movable blade block 4, concave parts 17 corresponding to the projected blades 16 are provided at positions between each of the upper and lower recessed parts A.