An exhaust gas purification system provided with a trapping device (6) arranged on an engine exhaust passage and trapping particulate matter in the exhaust gas, an ozone generator (21) for generating ozone, and an ozone adsorbent (22) able to adsorb ozone, wherein at least part of the ozone generated by said ozone generator is adsorbed by said ozone adsorbent and, when particulate matter trapped on said trapping device should be removed, ozone adsorbed on the ozone adsorbent is desorbed from the ozone adsorbent and supplied to the trapping device. Due to this, it is possible to use an ozone generator with a relatively low ozone generating ability to burn off PM trapped on a filter etc. efficiently.