PURPOSE: A connector marking device is provided to minimize efficiency lowering due to connection. CONSTITUTION: A ferrule(130) for measurement is inserted into an insertion recess and is connected to a fixing ferrule. A connection loss measuring unit is connected to the ferrule for measurement and measures optical connection loss. A ferrule rotation driving unit(150) rotates a ferrule for measurement. A stage driving unit(160) moves the ferrule for measurement toward the fixing ferrule. A marking unit(170) marks a low connection loss direction on the ferrule for measurement.
