An exhaust purification device for an internal combustion engine can achieve high NOx purifying performance independent of operating conditions of the engine. The exhaust purification device has a NOx purification catalyst (33) mounted in an exhaust pipe (4) of the internal combustion engine, adsorbing or occluding NOx in exhaust gas when the exhaust gas air/fuel ratio is made lean, and reducing the adsorbed or occluded NOx when the exhaust gas air/fuel ratio is made rich; a fuel reformer (50) mounted separately from the exhaust pipe (4), reforming fuel to produce a reducing gas containing hydrogen and carbon monoxide, and supplying the reducing gas into that part of the exhaust pipe (4) which is located upstream of the NOx purification catalyst (33); and enriching means for enriching the exhaust gas air/fuel ratio. When one or more of operating conditions are satisfied, the enriching means enriches the air/fuel ratio of mixed gas to be combusted in the engine and causes the fuel reformer (50) to supply the reducing gas into the exhaust pipe (4) to enrich the exhaust gas air/fuel ratio.