Exhaust purification system of internal combustion engine

An exhaust purification system of an internal combustion engine which is provided with

• an NOx storage reduction catalyst which is arranged in an engine exhaust passage, which stores NOx which is contained in exhaust gas when an air-fuel ratio of inflowing exhaust gas is lean, and which releases stored NOx when an air-fuel ratio of the inflowing exhaust gas becomes a stoichiometric air-fuel ratio or rich and
• an SOx trap material which is arranged in the engine exhaust passage upstream of the NOx storage reduction catalyst and which removes SOx which is contained in the exhaust gas, wherein,
• in the engine body, a main flow path which circulates lubrication oil of the engine body has connected to it a secondary flow path which bypasses the main flow path, while the secondary flow path has arranged in it a removal device which removes the sulfur constituent which is contained in the lubrication oil and has arranged in it an opening and closing device which opens and closes the secondary flow path, and
• when an SOx removal rate of the SOx trap material becomes a predetermined removal rate judgment value or less or when a concentration of the SOx which flows into the SOx trap material becomes a predetermined concentration judgment value or more, at least part of the lubrication oil which flows through the main flow path is made to flow into the secondary flow path and run through the removal device.