An exhaust purification device is provided to selectively perform a combustion purge control and an exhaust addition purge control in response to an operation state of the internal combustion engine. The combustion purge control process is performed in the case where a NOx occlusion amount of a NOx catalyst is larger than or equal to a first threshold value, and the exhaust addition purge control process is performed in the case where the NOx occlusion amount of the NOx catalyst is larger than or equal to a second threshold value which is larger than the first threshold value.