An abnormality detection apparatus for a particulate filter that is provided in an exhaust system of an internal combustion engine and traps particulate matter in exhaust gas. The abnormality detection apparatus includes: a sensor that is provided downstream of the particulate filter and detects the particulate matter; a removal device that removes the particulate matter trapped in the particulate filter based on an output of the sensor; and a determination device that determines whether the particulate filter is in an abnormal state based on a first stabilization time that has elapsed until the output of the sensor becomes stable after completion of removal of the particulate matter performed by the removal device.