To provide a turbocharger suppressing an exhaust energy loss, more immediately raising temperature of a turbine housing, and having superior strength.

When exhaust energy is high, for example, when an engine speed is high, an operating valve 8 is opened to allow exhaust gas having high exhaust energy to flow to a sub passage 7. Thereby, the temperature of the turbine housing is more immediately raised, and the exhaust energy loss is suppressed. When the exhaust energy is low, for example, when the engine speed is low, the operating valve 8 is closed to keep high-temperature exhaust gas in the sub passage 7. Thereby, the inside of the turbine housing is kept at high temperature, and the exhaust energy loss is suppressed. Or, the sub passage 7 functions as a heat-insulating layer to suppress the exhaust energy loss. Further, since a plurality of intakes 11 and discharge ports 12 are respectively arranged at intervals in the peripheral direction of an exhaust downstream duct portion, the supporting strength of "a partitioning wall partitioning an exhaust scroll and the sub passage 7" is increased.