Experiments have been conducted to investigate performance of compressed natural gas vehicle by single-bed and dual-bed type catalytic converter. All the catalysts was modifed to add to properly La, Zr and Ce concentration. The activity of methane oxidation varied as follows, Pd>Pt/Rh>Pt. Dual-bed type catalyst was better than single-bed type Pd catalysts in methane conversion. When NO was coexisted in mixture gas for investigating performance of catalysts, the conversion of methane oxidation was increased as many as NO concentration in mixture gas and the poison of NO was not effected to dual-bed type catalyst.