To provide an abnormality determination apparatus for a temperature detection device, improving the accuracy of abnormality determination.

The abnormality determination apparatus 1 for a temperature detection device detecting a temperature of exhaust gas emitted to an exhaust system 5, comprises: an upstream temperature acquiring means 2 acquiring a temperature of the exhaust gas upstream of an exhaust emission control device 7 as an upstream temperature; a downstream temperature sensor 11 detecting a temperature of exhaust gas downstream of the exhaust emission control device as a downstream temperature; downstream temperature estimation means 2a, 2 estimating the downstream temperature, so that a delay in temperature change with respect to the upstream temperature becomes longer than that when the fuel is being supplied; an abnormality determination means determining an abnormality of at least one of the upstream temperature acquiring means and downstream temperature sensor, depending on a result of comparison between the estimated downstream temperature TCAREF and the detected downstream temperature TCATA.