Abstract: An internal combustion engine with a dual turbocharger system includes a first turbocharger operated through an entire intake air quantity, a second turbocharger operated only at large intake air quantities, an exhaust bypass conduit bypassing a turbine of the second turbocharger, an exhaust bypass valve installed in the exhaust bypass conduit, and exhaust bypass valve opening control means for controlling at least one of a time to begin opening and a speed of opening the exhaust bypass valve. The exhaust bypass valve is opened before the turbocharger operation is switched from a "one-turbocharger-operation" to a "two-turbocharger-operation" so that the second turbocharger is run-up and a smooth transition can be obtained.