A control device for an internal combustion engine that includes: a reducing agent addition system that is configured to supply an ammonia-based reducing agent to a nitrogen oxide purification catalyst arranged in downstream of an exhaust passage by adding the ammonia-based reducing agent into the exhaust passage of the internal combustion engine through an addition valve, and a particulate matter removal filter that is provided in the exhaust passage at a location upstream of the addition valve and configured to trap particulate matter and of which a filter function is regenerable by burning the deposited particulate matter, the control device being characterized by further comprising: an exhaust gas temperature suppressor that, when it is not possible to add the ammonia-based reducing agent into the exhaust passage, suppresses an exhaust gas temperature in the exhaust passage to a lower temperature than the exhaust gas temperature when it is possible to add the ammonia-based reducing agent into the exhaust passage, wherein, when it is not possible to add the ammonia-based reducing agent into the exhaust passage, the exhaust gas temperature suppressor executes, as a temperature decreasing process of decreasing the exhaust gas temperature in the exhaust passage as compared to the exhaust gas temperature when it is possible to add the ammonia-based reducing agent into the exhaust passage, an upper limit setting process of setting an upper limit to a regeneration temperature of the particulate matter removal filter, and wherein, when it is not possible to add the ammonia-based reducing agent into the exhaust passage, the exhaust gas temperature suppressor sets an upper limit to the exhaust gas temperature through the upper limit setting process. a reducing agent addition system that is configured to supply an ammonia-based reducing agent to a nitrogen oxide purification catalyst arranged in downstream of an exhaust passage by adding the ammonia-based reducing agent into the exhaust passage of the internal combustion engine through an addition valve, and a particulate matter removal filter that is provided in the exhaust passage at a location upstream of the addition valve and configured to trap particulate matter and of which a filter function is regenerable by burning the deposited particulate matter, the control device being characterized by further comprising: an exhaust gas temperature suppressor that, when it is not possible to add the ammonia-based reducing agent into the exhaust passage, suppresses an exhaust gas temperature in the exhaust passage to a lower temperature than the exhaust gas temperature when it is possible to add the ammonia-based reducing agent into the exhaust passage, wherein, when it is not possible to add the ammonia-based reducing agent into the exhaust passage, the exhaust gas temperature suppressor executes, as a temperature decreasing process of decreasing the exhaust gas temperature in the exhaust passage as compared to the exhaust gas temperature when it is possible to add the ammonia-based reducing agent into the exhaust passage, an upper limit setting process of setting an upper limit to a regeneration temperature of the particulate matter removal filter, and wherein, when it is not possible to add the ammonia-based reducing agent into the exhaust passage, the exhaust gas temperature suppressor sets an upper limit to the exhaust gas temperature through the upper limit setting process. an exhaust gas temperature suppressor that, when it is not possible to add the ammonia-based reducing agent into the exhaust passage, suppresses an exhaust gas temperature in the exhaust passage to a lower temperature than the exhaust gas temperature when it is possible to add the ammonia-based reducing agent into the exhaust passage, wherein, when it is not possible to add the ammonia-based reducing agent into the exhaust passage, the exhaust gas temperature suppressor executes, as a temperature decreasing process of decreasing the exhaust gas temperature in the exhaust passage as compared to the exhaust gas temperature when it is possible to add the ammonia-based reducing agent into the exhaust passage, an upper limit setting process of setting an upper limit to a regeneration temperature of the particulate matter removal filter, and wherein, when it is not possible to add the ammonia-based reducing agent into the exhaust passage, the exhaust gas temperature suppressor sets an upper limit to the exhaust gas temperature through the upper limit setting process.