Provided is an exhaust fumes reduction device for an internal combustion engine. The device reduces the generation of exhaust fumes and improves output and fuel efficiency by smoothing the discharge flow of exhaust gas in a state additionally mounted at the end of an exhaust line of an internal combustion engine. The exhaust fumes reduction device includes; a housing pipe connected to the end of the exhaust port to discharge exhaust gas; a vortex pipe mounted inside the housing pipe to increase the speed of the exhaust gas introduced into the housing pipe and discharge the exhaust gas spirally; and an external pipe mounted on the outside of the housing pipe and in communication with the housing pipe to allow the outside air to flow in and to assist the smooth discharge of exhaust gas discharged to the housing pipe.