The present invention relates to an apparatus for cutting fine straw. The apparatus includes: a cutter body unit; a cutter conveying unit which includes a conveying roller to convey input straws; a cutter unit which cuts the straw; and an auxiliary device which is arranged between the cutter conveying unit and the cutter unit. The auxiliary device includes: a body member which forms an inlet to receive the straw; a pressing member which forms an outlet unit with the body member to discharge the straws and is rotatably coupled to the body member to allow the user to adjust the size of the outlet; and an elastic member which has a side installed onto the body member and another side in contact with the pressing member in order to apply elastic force to the pressing member in a direction that reduces the side of the outlet.
