In order to clarify the effect of the dopant concentration and phase transition on the proton conduction and proton concentration, the electrical conductivity and proton concentration were determined for La_1−xBa_xYb_0.5In_0.5O_3−δ (x = 0.1. 0.3. 0.5, 0.7). The phase transition from the orthorhombic system to the cubic system was over x = 0.3. The proton/deuteron isotope effect on the conductivity was observed for all samples at 673 K. The proton concentration was independent of the barium content above 673 K. The proton concentration increased with the barium content below 673 K, but the concentration ratio of the proton to dopant decreased following an increase in the barium concentration. It was determined that the dopant concentration and phase transition do not have an influence on the conduction and incorporation of protons into the La_1−xBa_xYb_0.5In_0.5O_3−δ.