Pore-free disks of La1-xSrxCoO3 (x = 0.4, 0.5, 0.6) as one of the mixed conductive perovskite-type oxides were successfully prepared, where a powder precursor having not yet the perovskite structure was selected as a starting material. The rate of oxygen permeation through the La1-xSrxCoO3 disk was found to increase with an increment in Sr content, and to be mainly controlled by the amount of oxygen vacancy. Effects of thickness of the disk and oxygen partial pressure on the oxygen permeation rate could be elucidated by the electrochemical transport equation. In conclusion, La1-xSrxCoO3 is a promising material for oxygen permeation at high temperatures.