Abstract: This invention relates to a device for reducing toxic wastes of diesel fuel and more particularly, to a novel-type device for reducing toxic wastes of diesel fuel. The device of this invention, being equivalent to a pre-treatment device, is mounted to the surface side of a fuel feed port at a diesel internal combustion engine so as to activate molecules in diesel fuel and their molecular movement. In particular, with a view to effective induction of electromagnetic wave and magnetic field, some supplemental equipments such as magnet, ceramic pole and coil are arranged on the device of this invention and based on this fabrication, perfect combustion conditions of diesel fuel may be provided in such a manner that some physicochemical changes are offered to diesel fuel, passing through the fuel feed port.