An estimated trapped amount (PM) that is an estimated value of an amount of particulate matter that is trapped in a particulate filter arranged in an engine exhaust passage is calculated based on an engine operating state, and PM removal control is performed when the estimated trapped amount exceeds an upper limit amount. Reference temperature increase control is performed to remove the particulate matter from the particulate filter, and an actual temperature that is the temperature of the particulate filter while the reference temperature increase control is being performed is detected. A reference temperature that is the temperature of the particulate filter when it is assumed that the reference temperature increase control has been performed when the amount of particulate matter trapped in the particulate filter is a reference initial trapped amount is stored in advance. The estimated trapped amount is corrected based on the actual temperature and the reference temperature.