With the aim of developing Cr-bearing rebars having required resistance to deteriorative environments prone to carbonation, ten types of steel bars having different Cr contents were embedded in concretes to fabricate specimens assuming such deteriorative environments. After being carbonated to the reinforcement level, these concretes were subjected to corrosion-accelerating cycles of heating/cooling and drying/wetting. The time-related changes in the corrosion area ratio and corrosion loss of the Cr-bearing rebars were then measured to investigate their corrosion resistance. The results revealed that the Cr content required for corrosion resistance in a simple carbonating environment was 5% or more. The corrosion-resisting performance of Cr-bearing reinforcement was particularly noticeable with a Cr content of 7% or more.