Abstract: A folding knife includes a movable piece that is attached to a blade and a handle so as to be relatively rotatable by a specific rotation angle with respect to the blade, and to rotate with respect to the handle together with the blade outside the specific rotation angle; a notch or a recess formed at a position near a rotating shaft portion on the back side of the blade; a protrusion that is formed at a position on the movable piece and in a shape corresponding to the notch or recess of the blade; and a rotation mechanism including the rotating shaft portion that allows the movable piece to rotate with respect to the blade only within a specific rotation angle.

Abstract: It is an object of the present invention to provide a folding knife with which, in its open state in which the blade is fully opened from the handle, a protrusion on the blade side can be prevented from hitting the thumb of a user who tries to push the knife down from above with respect to the object to be cut. This is a folding knife comprising a movable piece that is attached to the blade and the handle so as to be relatively rotatable by a specific rotation angle with respect to the blade, and to rotate with respect to the handle together with the blade outside the specific rotation angle; a notch or a recess formed at a position near a rotating shaft portion on the back side of the blade; a protrusion that is formed at a position on the movable piece and in a shape corresponding to the notch or recess of the blade; and a rotation mechanism that allows the movable piece to rotate with respect to the blade only within a specific rotation angle.