An internal combustion engine with an exhaust gas purification device is provided in which the NOx held in a NOx catalyst can be efficiently reduced and purified, and a sufficient amount of NOx can be reduced, thereby making it possible to regenerate the NOx catalyst over a wide range thereof. When processing of releasing and reducing the NOx held in the NOx catalyst 33 for purification, light oil is injected by an addition valve 37 so as to be supplied to the NOx catalyst 33 together with the exhaust gas, and after the droplet-like light oil adheres to the entire area of the NOx catalyst 33, the flow rate of the exhaust gas is decreased.