Abnormality determination device for engine system

An ECU carries out a program including the step (S100) of detecting a discharge air temperature TC and obtaining an estimated discharge air temperature TC(X) using an estimated discharge air temperature map, the step (S400) of setting a turbo abnormality determination flag when the discharge air temperature TC is higher than the estimated discharge air temperature TC(X) (YES in S300), the step (S500) of detecting an intake air temperature TIM, the step (S600) of calculating cooling efficiency of an intercooler from the discharge air temperature TC and the intake air temperature TIM, and the step (S800) of setting an intercooler abnormality determination flag when the cooling efficiency of the intercooler is decreased (YES in S700).