Tough gel membrane composed of a large amount of an ionic liquid and an inorganic/organic composite double-network (inorganic/organic DN ion gel membrane) was examined to remove toluene vapor from toluene vapor/N-2 mixed gas. The DN ion gel membrane with 80 wt% of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide showed higher toluene vapor permeability (more than 30,000 barrer) and toluene vapor/N-2 permselectivity (690) than the supported ionic liquid membrane. The toluene vapor permeability and toluene vapor/N-2 permselectivity were maintained under pressurized condition. It was confirmed that the toluene vapor permeation was limited by intramembrane diffusion of the dissolved toluene vapor.