Combustion experiments with polyethylene (PE) and PE-added goethite or hematite in various fractions were carried out using a combustion apparatus of fixed-bed semi-batch type. As a result, it is confirmed that benzene is formed during combustion for PE and PE-added hematite, while it is not formed for PE-added goethite. Furthermore, measurements of apparent activation energy in combustion are performed, and the oxidation mechanism of PE-added iron oxides is also studied.