To provide a pyrolyzer and a method thereof which purge a contaminant generated when heat is applied to food.

An oven contaminant pyrolyzer includes a heating means, a combustion tube, a combustion space, a connecting tube, and a ventilation part. The heating means is provided inside an oven cooking chamber, and is surrounded by the combustion tube to form the combustion space where air flows between the heating means and the combustion tube. The ventilation part is connected to the combustion tube via the connecting tube, moves air inside the cooking chamber to the combustion space, and exhausts the purged air to the outside. The ventilation part includes a fan which generates a flow of air. The connecting tube transmits an air pressure difference generated by the fan to the combustion tube, to generate a lower pressure in the cooking chamber than atmospheric pressure. The contaminant is not spread to the outside of the cooking chamber, and stays in the combustion space heated at 700°C or more by the heating means for at least 0.5 s or more to be thermally decomposed.