In this paper, perovskite-type La_0.9Sr_0.1(Ga_1-xFe_x)_0.8Mg_0.2O_3-δ(x=0-0.5) powders were prepared by soild state reaction, followed by estimation of phase structures and properties according to Fe contents and sintering conditions. Impurity phases as well as perovskite phase were observed in the powders which were calcined at 800 ℃ for 10h followed by sintering at 1300 ℃ for 10h. The smallest amount of the impurity phases was observed in the powder with the highest Fe content. The X-ray diffraction peaks corresponding to the 220 peak in pseudo cubic lattice were collected. The data were used for calculation of orthorhombic unit cell parameters by PROFITVZ program. Mean unit cell parameters (V^1/3) decreased with x at the Fe contents not more than 0.2 and increased with x at the Fe contents not less than 0.3. Electrical conductivity of the bar-like samples was measured as a function of temperature from 290K up to 1200K in air by a standard two-probe technique using platinum electrodes. The relationship between log(σT) and 1/T at 1kHz exhibited the Arrhenius behavior. Electrical conductivity increased with Fe contents. Particularly, Fe contents substantially contributed to electrical conductivity at lower temperature. In air, La_0.9Sr_0.1(Ga_1-xFe_x)_0.8Mg_0.2O_3-δ perovskite-type oxide showed the reversible elongation property in which the structural phase transition occurred at near 600 ℃.