We have investigated the influence of laser irradiation on the photoluminescence (PL) intensity of InGaAsN quantum wells (QWs) to emulate the performance degradation during device operation. The PL intensity was reduced with fast and slow components by laser irradiation with higher power densities. For a sample with a high nitrogen concentration of 1.3%, however, it is found that the PL intensity increases with irradiation time at laser power densities lower than ~240 kW/cm2. The improvement in the PL intensity can be explained by the fact that annihilation of nitrogen-related as-grown defects by laser irradiation. The amount and rate of the PL intensity degradation of InGaAsN QWs with different N and In compositions by laser irradiation are also discussed. Thus, it is demonstrated that real-time PL measurements with high power density excitation are useful to the analysis of degradation processes.