A device for detecting a lump is provided to prevent malfunction by guiding a wire to a penetration hole of a hitching cylinder by vertical and horizontal guide rollers. A device(10) for detecting a lump detects the lump on a surface of a wire(1). A circular hole is formed to pass through a main body(11). A hitching cylinder is inserted into a circular hole. The hitching cylinder is comprised of two circular half-bodies(21). The penetration hole is formed in the center of the hitching cylinder. A diameter of the penetration hole is identical to an external diameter. The wire is inserted into the penetration hole. A limit switch(30) is connected to a controller(40). If the hitching cylinder pushes the limit switch, the switch turns off the system.