A device for purifying the exhaust gas of an internal combustion engine is disclosed. The device has a particulate filter arranged in the exhaust system on which the trapped particulates are oxidized, and a reversing mechanism for reversing the exhaust gas upstream side and the exhaust gas downstream side of the particulate filter. The particulate filter has a trapping wall. The trapping wall has a first trapping surface and a second trapping surface. The reversing mechanism reverses the exhaust gas upstream side and the exhaust gas downstream side of the particulate filter so that the first trapping surface and the second trapping surface are used alternately to trap the particulates. The device can improve the amount of particulates that can be oxidized and removed on the particulate filter.