PURPOSE: To cut off a blade by deforming a cutter supporting part and deal with the cut-off blade safety by providing a cutter with a cutter main body having a guiding member, a blade coming-in and out part of the guiding member having an elastic deforming supporting part projected therefrom.

CONSTITUTION: A deforming supporting part with a blade coming in and out part 2 which is projected from a guiding member opening blade coming in and out part 4 is provided in a supporting part 13. An elastic plate 10 is provided in a guiding member opening blade coming-in and out part. A hollow 6 is provided in a guiding member opening back side supporting member. A projection 8 is provided in the hollow 6 in the supporting part. The supporting part 13 is covered with a lid. The elastic plate 10 is projected toward an opening of the supporting part hollow so as to push a cut-off blade into the hollow 6 in the deforming supporting part with blade coming-in and out part 2 and prevent the cut-off blade from coming off the blade coming-in and out part of the deforming supporting part 2. A supporting part hollow opening 7 is provided for communication between a hollow and the inside of the supporting part 13 on the back side of the guiding part opening and for carrying the cut-off blade to the inside of the supporting part 13.