To estimate axial-symmetric plastic anisotropy of AZ31B (Mg-3mass%Al-1mass%Zn) magnesium alloy extruded bar, the Mg specimen with a cube shape was compressed in several directions at various temperatures. The compressive stress-strain curves in the r-, θ-, and z-direction were measured by cube compression test. And the maximum strain ratios of ε_θ/ε_z = 11 and ε_r/ε_z = 10-11 were measured at the temperatures of 100-200℃. The validity of the obtained anisotropic coefficients of Hill's quadratic anisotropic criterion was investigated by the FE analysis for the plastic deformation of the Mg alloy. In the FE analysis, the plastic deformation of the Mg specimen with a ring shape was calculated with/without considering plastic anisotropy. It was found that the estimated frictional coefficient with the FE analysis with considering axial-symmetric plastic anisotropy was higher than that with the conventional FE analysis for the isotropic material.