Low viscosity ionic liquids (ILs) composed of a cation with methoxy group and an aprotic heterocyclic anion (AHA) with highly nucleophilic amino group were synthesized and examined as a CO2 carrier of facilitated transport membranes. Due to the low viscosity of the AHA-type ILs after CO2 absorption, the AHA-type IL-based membrane showed high CO2 permeability (ca. 3900 barrer) with 200 of CO2/CH4 selectivity under dry condition at 323 K, which was much higher than that of amino acid ILs-based membrane (ca. 150 barrer with ca. 50 of CO2/CH4 selectivity).