An exhaust purification system of an internal combustion engine comprising an NOX holding material arranged in an engine exhaust passage, having a catalyst metal containing silver, holding NOX contained in the exhaust gas in the form of silver nitrate by the catalyst metal when an air-fuel ratio of inflowing exhaust gas is lean, and releasing the held NOX if the air-fuel ratio of the inflowing exhaust gas becomes a stoichiometric air-fuel ratio or rich. The NOX holding material has a scatter temperature at which catalyst metal scatters in the form of silver nitrate if the temperature rises. When it is time to perform control raising the temperature of the NO holding material to the scatter temperature or above, the NOX held in the NOX holding material is released by making the air-fuel ratio of the exhaust gas flowing into the NO holding material the stoichiometric air-fuel ratio or rich.