In order to improve oxygen reduction performances of an air electrode using perovskite type La 0.7 Ca 0.3 CoO 3 as an electrocatalyst, a layered double hydroxide (LDH) containing magnesium and aluminum was examined as an ionconducting additive. Although the addition of LDH impeded gas permeation of the catalyst layer of the electrode, it was effective in reducing charge transfer resistance of the electrode, and as a result, the oxygen reduction reaction of the air electrode was remarkably enhanced.