Disclosed is a combustion apparatus for both firewood and pellet fuel comprising: a combustion chamber in which wood fuel including firewood or a pellet is stacked; an air supply unit provided with an air supply pipe and a gap-maintaining member and including a nozzle connected to the air supply pipe and configured to spray air toward the wood fuel in a side direction thereof; and an operating unit configured to force the gap-maintaining member to come into contact with one side of the wood fuel to continuously maintain a constant gap between the nozzle and the wood fuel during combustion.