An ammonia burning internal combustion engine using ammonia as fuel comprises an ammonia feed device feeding ammonia to a combustion chamber and a temperature/pressure raising system raising the temperature or raising the pressure of ammonia fed to the ammonia feed device. The temperature/pressure raising system raises the temperature or raises the pressure of ammonia by energy produced along with the operation of the internal combustion engine. As a result, an ammonia burning internal combustion engine maintaining high energy efficiency for the internal combustion engine as a whole or a vehicle mounted with the internal combustion engine as a whole while appropriately controlling the temperature or pressure of ammonia fed to an ammonia injector is provided.