An exhaust purification system of an internal combustion engine provided with an exhaust purification catalyst which reacts NOX and hydrocarbons. The exhaust purification catalyst includes an upstream side catalyst and a downstream side catalyst. The upstream side catalyst has an oxidation ability, while the downstream side catalyst carries precious metal catalyst particles on the exhaust flow surface and is formed with basic exhaust flow surface parts. The exhaust purification catalyst can make the concentration of hydrocarbons vibrate by within a predetermined range of amplitude and by within a predetermined range of period so as to partially oxidize the hydrocarbons or produce reducing intermediates at the upstream side catalyst. When the temperature of the upstream side catalyst is less than a first judgment temperature and the temperature of the downstream side catalyst is higher than a second judgment temperature, the temperature of the upstream side catalyst is made to rise.