Ammonia combustion internal combustion engine

Inside of a combustion chamber, ammonia is made to burn well. Inside of the combustion chamber 5, in addition to ammonia, reformed gas which is reformed inside of the reformer 20 is fed. When the reforming ability of the reformer 20 is a predetermined reforming ability or less, the ammonia ratio is made to increase over the ammonia ratio after completion of warmup which is preset according to the operating state of the engine, and secondary air is fed from the secondary air feed device 37 into the engine exhaust passage upstream of the exhaust purification catalyst 19.