Exhaust gas purifying apparatus for internal combustion engine

An exhaust gas purifying system for an internal combustion engine (1) comprises an oxidation catalyst (14) having an oxidizing ability, provided in an exhaust passage of an internal combustion engine, a filter (18) that can trap particulate matter contained in exhaust gas, provided in the exhaust passage downstream of said oxidation catalyst (14), temperature detection means (31,32) for detecting or estimating temperatures of an upstream portion and a downstream portion of said filter (18), fuel supply means (17) for supplying fuel into exhaust gas flowing into said oxidation catalyst (14), and clogging determination means adapted to make such a determination that there is clogging of said oxidation catalyst (14), if the difference in the temperature of the upstream portion and the temperature of the downstream portion detected by said temperature detection means (31,32) is larger than a predetermined value while regeneration control for said filter (18) is performed by supplying fuel to exhaust gas flowing into said oxidation catalyst (14) by said fuel supply means (17). In the exhaust gas purifying system for an internal combustion engine having an oxidation catalyst (14) and a filter (18) provided in series in an exhaust passage as per the above, it is possible to determine clogging of the oxidation catalyst (14) with improved accuracy.