In order to estimate the rebar corrosion rate in carbonated concrete, reinforced concrete specimens acceleratedly carbonated were subjected to a 5-year exposure test. In concrete specimens, rebars were arranged in lattice direction. Test results showed that the average corrosion rate of the lower part of lattice rebars was abut 0.002mm/yr. Based on the above-mentioned test results and the past references, deterioration prediction of concrete structures was carried out. As the result, it was considered that bearing capacity of concrete structures is not seriously hampered by rebar corrosion. However, the possibility of deterioration such as the spalling of cover concrete is rather high, as carbonetion precedes.