Abnormality-determining device for turbo-supercharger

An abnormality-determining device for a turbosupercharger, which properly decides whether or not to execute the abnormality determination of variable vanes during a time period from the start of an internal combustion engine until the variable vanes become non-stuck, thereby being capable of preventing a turbosupercharger and devices of an exhaust system from becoming faulty, and at the same time is capable of improving drivability. The abnormality-determining device determines whether or not the variable vanes are abnormal, and at the same time determines whether or not the variable vanes are non-stuck. Further, during the time period after the start of the engine until it is determined that the variable vanes are non-stuck, the abnormality-determining device determines whether or not to execute abnormality determination of the variable vanes based on a relationship between the detected boost pressure and the set target boost pressure.