An anomaly determination unit includes an EGR amount acquisition section configured to acquire an actual amount of an EGR amount, which is a flow rate of EGR gas; an estimation amount computation section configured to compute an estimated amount of the EGR amount based on a working gas pressure, which is a pressure of working gas in which the EGR gas and intake air are mixed, an EGR temperature, which is a temperature of the EGR gas immediately upstream of an EGR valve, an EGR pressure, which is a pressure of the EGR gas immediately upstream of the EGR valve, and an opening degree instruction value for the EGR valve; and a determination section configured to determine the presence or absence of an anomaly in the EGR valve based on the divergence between the actual amount of the EGR amount and the estimated amount.
