Abstract: A slider is attached to a cutter main body of an optical fiber cutter in a forward/backward movable state. A round blade member for making a scratch in an optical fiber is attached to the slider in a rotatable state. An operation lever pin for changing over rotation operation modes from one to another is attached to one end side of a pin member which penetrates a wall of the cutter main body. The rotation operation modes include a non-rotation mode for preventing the round blade member from being rotated and a continuous rotation mode for rotating the round blade member by a predetermined angle with every backward movement of the slider.