An internal combustion engine wherein a hydrocarbon feed valve (15) and an exhaust purification catalyst (13) are arranged inside of an engine exhaust passage. At the time of engine operation, the amount of injection of hydrocarbons from the hydrocarbon feed valve (15) is controlled so that an amplitude of change of concentration of hydrocarbons which flow into the exhaust purification catalyst (13) becomes within a predetermined range of amplitude, and the injection period of hydrocarbons from the hydrocarbon feed valve (15) is controlled so that a concentration of hydrocarbons which flow into the exhaust purification catalyst (13) vibrates within a predetermined range of period. The exhaust purification catalyst (13) is formed so that a deposition ability of hydrocarbons to a downstream side part of the exhaust purification catalyst (13) becomes higher than a deposition ability of hydrocarbons to an upstream side part of the exhaust purification catalyst (13).