To provide a carbonization oven and a carbonization oven unit that can advantageously correspond to a variety of raw materials typified by organic wood waste, for example, plant seeds.

The carbonization oven 1 is equipped with the dry distillation chamber 2 that has the raw material feeding inlet opened 90, through which the raw material is fed, and has a multistage structure inside in the vertical direction, the adiabatic walls 4 that constitutes the combustion chamber 3 of the circular cross section surrounding the multistage dry distillation chamber from the outside, the gas pipe 5 that allows the dry distillation chamber 2 and the combustion chamber 3 to communication with each other and has the fire opening W in the combustion chamber 3 and heats the combustion chamber 3 by burning the dry-distilled gas formed in the dry distillation chamber 2 and the exhaustion opening 8 communicating with the combustion chamber 3. The structure of the fire opening W of the gas pipe 5 is made variable in the diameter. The gas pipe is made adjustable in the distance between the fire opening W and the exhaustion outlet 8.