Disclosed is a blade snap-off holder which enables a safe, easy and smooth operation for snapping off a blade tip of a cutter knife. The holder has an insertion opening on its wall. A tip of a knife blade inserted through the opening is received in a groove of a rotary member located inside the holder. The rotation axis of the rotary member extends substantially parallel to the score of the knife blade. When the rotary member is rotated and a bending force is applied to the tip of the knife blade, the blade tip received in the groove of the rotary member can be snapped off. A user only grasps this holder in one hand and rotates the operation lever with a finger, and then a blade tip can be snapped off cleanly and easily without any subtle control of a force.