Provided is an exhaust gas cleaner by which nitrogen oxides contained in an exhaust gas can be efficiently removed in a wide temperature range from a low temperature. The exhaust gas cleaner (10) is for use in purifying the exhaust gas discharged from an internal combustion engine (15) in which fuel is fed under periodical rich or lean conditions and burned. The cleaner (10) comprises: a reforming means (11) which generates a reforming gas comprising hydrogen and carbon monoxide; a means of low-temperature oxidation (12) which contains palladium and which thereby can oxidize and adsorb nitrogen oxides at low temperatures and oxidize the hydrogen and carbon monoxide; and a purifying means (13) which under lean conditions adsorbs nitrogen oxides and which under rich conditions releases the adsorbed nitrogen oxides and removes the released nitrogen oxides with the hydrogen and carbon monoxide present in the channel. By contriving the layout of the reforming means (11), means of low-temperature oxidation (12), and purifying means (13), nitrogen oxides contained in an exhaust gas can be removed in a wide temperature range from a low temperature.