An exhaust gas purifying system includes, an internal combustion engine, an exhaust passage of exhaust gas from the internal combustion engine, a hydrogen-catalyst provided in the exhaust passage, an NOx purifying catalyst provided on a downstream of the hydrogen-catalyst of the exhaust passage to reduce nitrogen oxides, and a control unit. The hydrogen-catalyst has a function of transmitting or generating hydrogen. In the purifying system, the control unit 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 is lowered in intermittent enrichment of the air/fuel ratio.