An exhaust emission control device comprises a selective reduction catalyst for reacting NOx in an exhaust gas with ammonia, means for adding a urea water into the exhaust gas upstream of the catalyst and a cylindrical mixing pipe as a connection between the adding means and the catalyst, an entry end of the mixing pipe being formed with circumferential opening sections and provided with guide fins for guiding the exhaust gas to the opening sections tangentially of the entry end to provide a mixer structure, the adding means being arranged centrally on the entry end of the mixing pipe and directed toward an exit end of the mixing pipe for addition of the urea water into a swirling flow of the exhaust gas caused by the mixer structure. The opening sections are formed along the swirling flow.