To enhance a purification rate of hot air by increasing a recovery rate of ash and soot.

This combustion device 100 includes: a pellet burner 110 with a burner port 111 burning a burning object and supplying combustion heat; a first combustion furnace 120 guiding combustion heat supplied from the burner port 111 upwardly; a second combustion furnace 130 connected to the first combustion furnace 120 by a connection pipe 140; and a combustion heat discharge port 134 provided in a vertical intermediate portion of the second combustion furnace 130 and discharging the combustion heat from the second combustion furnace 130. The connection pipe 140 interconnects a position on the upper side from the burner port 111 of the first combustion furnace 120 and a position on the upper side from the combustion heat discharge port 134 of the second combustion furnace 130.