An abnormality determination device for an EGR device, which is capable of determining the abnormality of the EGR device properly without interrupting the EGR operation. An ECU of an internal combustion engine detects an amount of fresh air drawn into a combustion chamber of the engine, carries out feedback control of the fresh air amount such that the detected fresh air amount converges to a predetermined target fresh air amount by controlling an opening of a throttle valve disposed in an intake system of the engine during execution of EGR by the EGR device. The ECU obtains a decreasing degree parameter which represent a degree of decrease in the fresh air amount caused by the feedback control, and determines abnormality of the EGR device based on the obtained decreasing degree parameter.