An exhaust system, comprising: an exhaust pipe connected to an engine, the exhaust gas generated at the engine passing through the exhaust pipe; an oxidizing catalyst mounted on the exhaust pipe downstream of the engine and adapted to oxidize hydrocarbon contained in the exhaust gas; a particulate filter mounted on the exhaust pipe downstream of the oxidizing catalyst, coated with a selective reduction catalyst which is adapted to reduce nitrogen oxides contained in the exhaust gas by an injection of a reducing agent, and adapted to trap particulate matters contained in the exhaust gas; a controller adapted to control a regeneration of the particulate filter and the injection of the reducing agent; a first tank adapted to store therein the reducing agent; a first pump adapted to pump the reducing agent stored in the first tank; and a first injector adapted to receive the reducing agent from the first pump and to inject the same to the exhaust gas; characterized in that the controller is adapted to control a supply to the exhaust gas of an oxygen storage capacity material together with the reducing agent or separately from the reducing agent, wherein the exhaust system further comprises: a second tank adapted to store therein the oxygen storage capacity material; a second pump adapted to pump the oxygen storage capacity material stored in the second tank; and a second injector adapted to receive the oxygen storage capacity material from the second pump and to inject the same to the exhaust gas, wherein the first tank is disposed in the second tank, and wherein the oxygen storage capacity material stored in the second tank prevents the reducing agent stored in the first tank from freezing. an exhaust pipe connected to an engine, the exhaust gas generated at the engine passing through the exhaust pipe; an oxidizing catalyst mounted on the exhaust pipe downstream of the engine and adapted to oxidize hydrocarbon contained in the exhaust gas; a particulate filter mounted on the exhaust pipe downstream of the oxidizing catalyst, coated with a selective reduction catalyst which is adapted to reduce nitrogen oxides contained in the exhaust gas by an injection of a reducing agent, and adapted to trap particulate matters contained in the exhaust gas; a controller adapted to control a regeneration of the particulate filter and the injection of the reducing agent; a first tank adapted to store therein the reducing agent; a first pump adapted to pump the reducing agent stored in the first tank; and a first injector adapted to receive the reducing agent from the first pump and to inject the same to the exhaust gas; characterized in that the controller is adapted to control a supply to the exhaust gas of an oxygen storage capacity material together with the reducing agent or separately from the reducing agent, wherein the exhaust system further comprises: a second tank adapted to store therein the oxygen storage capacity material; a second pump adapted to pump the oxygen storage capacity material stored in the second tank; and a second injector adapted to receive the oxygen storage capacity material from the second pump and to inject the same to the exhaust gas, wherein the first tank is disposed in the second tank, and wherein the oxygen storage capacity material stored in the second tank prevents the reducing agent stored in the first tank from freezing. a second tank adapted to store therein the oxygen storage capacity material; a second pump adapted to pump the oxygen storage capacity material stored in the second tank; and a second injector adapted to receive the oxygen storage capacity material from the second pump and to inject the same to the exhaust gas, wherein the first tank is disposed in the second tank, and wherein the oxygen storage capacity material stored in the second tank prevents the reducing agent stored in the first tank from freezing.