Exhaust gas purifying catalyst

An exhaust gas purifying system includes, an internal combustion engine (1), an exhaust passage of exhaust gas from the internal combustion engine (1), a hydrogen-catalyst (7) provided in the exhaust passage, an NOx purifying catalyst (8) provided on a downstream of the hydrogen-catalyst (7) of the exhaust passage to reduce nitrogen oxides, and a control unit (11). The hydrogen-catalyst (7) has a function of transmitting or generating hydrogen. In the purifying system, the control unit (11) executes enrichment condition control for reducing an air/fuel ratio (A/F)r during enrichment to prolong a time of enrichment (tr) as a flow rate of exhaust gas emitted from the internal combustion engine (1) is lowered in intermittent enrichment of the air/fuel ratio.