An exhaust gas purifying system for an internal combustion engine includes a first exhaust passage (22a) and a second exhaust passage (22b) into which an exhaust passage (21) of the internal combustion engine is bifurcated. NOx storage reduction catalysts (23a, 23b) and particulate filters (24a, 24b) are provided in each of the exhaust passages (22a, 22b). Fuel is supplied from a fuel valve (32) when NOx is to be released from the NOx storage reduction catalysts (23a, 23b). At a timing when the supplied fuel attaches to the NOx storage reduction catalysts (23a, 23b), one of exhaust control valves, for example, a first exhaust control valve (26a) is temporarily closed so as to keep the air-fuel ratio of exhaust gas rich. When NOx is released from the NOx storage reduction catalysts (23a, 23b) next time, a second exhaust control valve (26b) is temporarily closed after the fuel is supplied.