An abnormality determination apparatus for a particulate filter, comprising: a particulate filter provided in an exhaust passage of an internal combustion engine to collect particulate matter present in an exhaust gas discharged from the internal combustion engine; a particulate matter deposition amount detection device provided in the exhaust passage downstream of the particulate filter, wherein the particulate matter deposition amount detection device includes a detecting element that detects the particulate matter that flows toward the particulate matter deposition amount detection device and that is not trapped by the particulate filter, and the particulate matter deposition amount detection device outputs a value corresponding to a deposition amount of the particulate matter deposited on the detecting element; and an abnormality determination portion that determines, whether an abnormality is present in the particulate filter based on a gradient of an output waveform of the particulate matter deposition amount detection device, the abnormality determination apparatus, characterized in that: the abnormality determination portion determines that the abnormality is present in the particulate filter if the gradient of the output waveform exceeds a reference value between an abnormal state of the particulate filter and a normal state of the particulate filter, the particulate matter deposition amount detection device executes a detecting element regeneration control to remove the particulate matter deposited on the detecting element, and the abnormality determination portion determines that the abnormality is present in the particulate filter based on the gradient of the output waveform after an output of the particulate matter deposition amount detection device has become zero by the detecting element regeneration control. a particulate filter provided in an exhaust passage of an internal combustion engine to collect particulate matter present in an exhaust gas discharged from the internal combustion engine; a particulate matter deposition amount detection device provided in the exhaust passage downstream of the particulate filter, wherein the particulate matter deposition amount detection device includes a detecting element that detects the particulate matter that flows toward the particulate matter deposition amount detection device and that is not trapped by the particulate filter, and the particulate matter deposition amount detection device outputs a value corresponding to a deposition amount of the particulate matter deposited on the detecting element; and an abnormality determination portion that determines, whether an abnormality is present in the particulate filter based on a gradient of an output waveform of the particulate matter deposition amount detection device, the abnormality determination apparatus, characterized in that: the abnormality determination portion determines that the abnormality is present in the particulate filter if the gradient of the output waveform exceeds a reference value between an abnormal state of the particulate filter and a normal state of the particulate filter, the particulate matter deposition amount detection device executes a detecting element regeneration control to remove the particulate matter deposited on the detecting element, and the abnormality determination portion determines that the abnormality is present in the particulate filter based on the gradient of the output waveform after an output of the particulate matter deposition amount detection device has become zero by the detecting element regeneration control. the abnormality determination portion determines that the abnormality is present in the particulate filter if the gradient of the output waveform exceeds a reference value between an abnormal state of the particulate filter and a normal state of the particulate filter, the particulate matter deposition amount detection device executes a detecting element regeneration control to remove the particulate matter deposited on the detecting element, and the abnormality determination portion determines that the abnormality is present in the particulate filter based on the gradient of the output waveform after an output of the particulate matter deposition amount detection device has become zero by the detecting element regeneration control.