An internal combustion engine, wherein an exhaust purification catalyst (13) and a hydrocarbon supply valve (15) are arranged in an engine exhaust passage, the internal combustion engine being provided with a low-pressure exhaust gas recirculation device (LPL) for recirculating exhaust gas downstream of the exhaust air purification catalyst (13). When a lock up clutch (66) in a torque converter (27) should engage, non-sliding engagement of the lock up clutch (66) is prohibited in a case where an exhaust gas recirculation action is performed by the low-pressure exhaust gas recirculation device (LPL) and hydrocarbons are sprayed from the hydrocarbon supply valve (15) at predetermined cycles.