An anomaly determination unit to determine presence or absence of an anomaly in an EGR valve of an EGR device of an engine, the anomaly determination unit comprising: an exhaust pressure computation section configured to compute an exhaust pressure (Pem), which is a pressure within an exhaust manifold; a working gas amount computation section configured to compute a working gas amount (Gwg), which is a flow rate of a working gas supplied to cylinders of the engine where the working gas is a mixture of EGR gas and intake air, based on a computational equation that includes, as variables, a working gas pressure (Pwg), which is a pressure of the working gas flowing in an intake passage of the engine downstream of a connection portion between the intake passage and an EGR passage, a working gas temperature (Twg), which is a temperature of the working gas within an intake manifold of the engine, and an engine speed (Ne); the anomaly determination unit is characterized by further comprising: an EGR amount acquisition section configured to acquire an actual amount of an EGR amount (Gr), which is a flow rate of the EGR gas, by subtracting an intake air amount (Ga), which is an air amount received by the engine, from the working gas amount (Gwg); a pressure loss computation section configured to compute a pressure loss of the EGR gas (ΔPr) upstream of the EGR valve based on the EGR amount (Gr); an EGR pressure computation section configured to compute an EGR pressure (Pr), which is a pressure of the EGR gas immediately upstream of the EGR valve, by subtracting the pressure loss (ΔPr) from the exhaust pressure (Pem); an estimation amount computation section configured to compute an estimated amount of the EGR amount (EGr) based on the working gas pressure (Pwg), an EGR temperature (Tr), which is a temperature of the EGR gas immediately upstream of an EGR valve, the EGR pressure (Pr) computed by the EGR pressure computation section, and an opening degree instruction value (θrc) for the EGR valve; and a determination section configured to determine presence or absence of an anomaly in the EGR valve based on a divergence (ΔGr) between the actual amount of the EGR amount (Gr) and the estimated amount (EGr). an exhaust pressure computation section configured to compute an exhaust pressure (Pem), which is a pressure within an exhaust manifold; a working gas amount computation section configured to compute a working gas amount (Gwg), which is a flow rate of a working gas supplied to cylinders of the engine where the working gas is a mixture of EGR gas and intake air, based on a computational equation that includes, as variables, a working gas pressure (Pwg), which is a pressure of the working gas flowing in an intake passage of the engine downstream of a connection portion between the intake passage and an EGR passage, a working gas temperature (Twg), which is a temperature of the working gas within an intake manifold of the engine, and an engine speed (Ne); the anomaly determination unit is characterized by further comprising: an EGR amount acquisition section configured to acquire an actual amount of an EGR amount (Gr), which is a flow rate of the EGR gas, by subtracting an intake air amount (Ga), which is an air amount received by the engine, from the working gas amount (Gwg); a pressure loss computation section configured to compute a pressure loss of the EGR gas (ΔPr) upstream of the EGR valve based on the EGR amount (Gr); an EGR pressure computation section configured to compute an EGR pressure (Pr), which is a pressure of the EGR gas immediately upstream of the EGR valve, by subtracting the pressure loss (ΔPr) from the exhaust pressure (Pem); an estimation amount computation section configured to compute an estimated amount of the EGR amount (EGr) based on the working gas pressure (Pwg), an EGR temperature (Tr), which is a temperature of the EGR gas immediately upstream of an EGR valve, the EGR pressure (Pr) computed by the EGR pressure computation section, and an opening degree instruction value (θrc) for the EGR valve; and a determination section configured to determine presence or absence of an anomaly in the EGR valve based on a divergence (ΔGr) between the actual amount of the EGR amount (Gr) and the estimated amount (EGr). an EGR amount acquisition section configured to acquire an actual amount of an EGR amount (Gr), which is a flow rate of the EGR gas, by subtracting an intake air amount (Ga), which is an air amount received by the engine, from the working gas amount (Gwg); a pressure loss computation section configured to compute a pressure loss of the EGR gas (ΔPr) upstream of the EGR valve based on the EGR amount (Gr); an EGR pressure computation section configured to compute an EGR pressure (Pr), which is a pressure of the EGR gas immediately upstream of the EGR valve, by subtracting the pressure loss (ΔPr) from the exhaust pressure (Pem); an estimation amount computation section configured to compute an estimated amount of the EGR amount (EGr) based on the working gas pressure (Pwg), an EGR temperature (Tr), which is a temperature of the EGR gas immediately upstream of an EGR valve, the EGR pressure (Pr) computed by the EGR pressure computation section, and an opening degree instruction value (θrc) for the EGR valve; and a determination section configured to determine presence or absence of an anomaly in the EGR valve based on a divergence (ΔGr) between the actual amount of the EGR amount (Gr) and the estimated amount (EGr).