This paper experimentally investigates an influence of localized corrosion of steel bars embedded in concrete on structural performance of reinforced concrete (RC) beams by flexural loading test. The localized corrosion was produced by controlling the area of direct current impression in which a wet sponge was attached to the limited part of the bottom surface of RC beam. As a result, it was possible to estimate the first yield load and deformability of RC beam by using the maximum loss in cross-sectional area of steel bars, even if steel bars showed localized corrosion. However, the maximum loads of RC beams were not adequately estimated by the maximum loss in cross-sectional area. After the first yield, influences of localized corrosion of steel bars on load carrying capacity and deformability were varied depending on the position of corrosion.