For corrosion prevention method of steel bars in concrete structures damaged by salt attack under marine environments, a cathodic protection method has been suggested.
　This study was conducted to examine the current flow between anode area and cathode area, and the polarization amount of steel bars in concrete under both macro corrosion cell and cathodic protection.
　Major findings are as follows:
(1) As for the relation between macro corrosion current and Aa/Ac ratio (the ratio of anode area to cathode area fo steel bars in concrete), the smaller was the Aa/Ac ratio, the larger was the current density.
(2) Increase of polarization amount was larger at cathodic area than that at anode area.
(3) Protective current density for satisfing the 100m V criterion was about 10mA/m2(Aa/Ac:1/1～10/1) and about 22～29mA/m2 (Aa/Ac:1/10～1/2).