An object of the present invention is to provide a new frameless catalytic thermal oxidation device capable of treating concentrations of harmful materials including NOx at a low temperature. Further, another object of the present invention is to provide a frameless catalytic thermal oxidation device capable of minimizing the occurrence of THC and minimizing a risk of accidents and environmental pollution which may occur in maintenance operations. According to the objects, the present invention provides a cartridge-type thermal oxidation device capable of being separated for maintenance, wherein a cartridge internal structure is configured so that the time while the material to be treated stays in a zone with the catalyst is increased, and a member capable of dropping and collecting powder generated by thermal oxidation reaction is configured.