To provide a very compact and powerful exhaust system to exercise an effective influence on an exhaust gas temperature.

This system comprises an exhaust gas treating device 18; and a temperature control device 14 arranged in an exhaust passage running between the exhaust gas treating device and an internal combustion engine 10 and containing an outer exhaust passage 26 and an inner exhaust passage 24 surrounded with the outer exhaust passage. In this case, the outer exhaust passage 26 further incorporates a cooling element, by which an exhaust gas heat is guided to the outside and higher flow passage resistance is provided by exhaust gas flowing through in comparison with that of the inner exhaust passage. The inner exhaust passage 24 incorporates an exhaust flap valve 34 arranged in an outflow end region. By closing a flap, exhaust gas flows through only the outer exhaust passage and is more powerfully cooled. To improve the light off characteristics of the exhaust gas treating device 18 is a spot situated downstream, a converter 32 for starting may be arranged in the inner exhaust passage to further rapidly purify exhaust gas after the starting of an engine.