To use a compact supercharger in comparison with the exhaust quantity of an engine by lengthening the flowing time of exhaust gas in an EGR passage until cooling water temperature reaches a set temperature, thereby enhancing heating effect and regulating exhaust pressure.

An EGR passage 10 connecting an exhaust manifold 4 to an intake manifold 3 is piped in such a way as to be inserted through the inside of a water jacket 2a of an engine 2, and cooling water is heated by the heat of exhaust gas flowing in the EGR passage 10 to enhance heating effect. When water temperature detected by a water temperature sensor 21 is in a range of the set water temperature or lower, an ECU 20 opens an auxiliary valve 13 when an EGR valve 1 is closed. Exhaust gas therefore passes the EGR passage 10 and a by-pass passage 12 and is exhausted to an exhaust pipe 9, bypassing a turbosupercharger 5. When exhaust pressure (turbine exhaust presser) detected by a pressure sensor 25 exceeds the set pressure, the auxiliary valve 13 is opened to regulate exhaust pressure.