In this paper, non-destructive evaluation methods for the quality of vertical joints influencing rebar corrosion in patch repaired RC members were investigated. The relation between the quality of vertical joints and the generation of rebar corrosion due to salt attack was also confirmed. As a result, the bonding status at vertical joint was evaluated effectively using the difference of impedance before and after watering the joint by applying the two-electrode method. The quality of existing concrete was reflected in spectrum intensity by applying the impact elastic wave method. Furthermore, it was found that the difference of electric resistivity between the patch repaired part and the existing concrete was effective for evaluating rebar corrosion. These methods detected the difference of qualities of vertical joints in relation to the generation of corrosion. Finally, a concept flowchart for evaluating quality of vertical joints influencing rebar corrosion in patch repaired RC members was presented.