ZnO thin-film sensors were fabricated by RF magnetron sputtering method. $quot;`he composition of the device material was 4 wt. % Al₂O₃, 1 wt. % TiO₂ and 0.2 wt. V₂O_5 on the basis of ZnO material for developing the high sensitive TMA gas sensor which have an appropriate resistivity and the stability for practical use. They were also grown on the SiO₂/Si substrates heated at 250 ℃ under a pure oxygen pressure of about 10 mTorr with a power of about 80 watts for 10 minutes. So as to enhance the stability of the resistivity, the thin films were annealed from 400 ℃ to 800 v. The sensors made with the thin film which were annealed at 700 ℃ for 60 minutes in pure oxygen gas exhibited a good sensing properties for TMA gas. The thin film grown at this condition showed the maximum sensitivity of 550 in TMA gas concentration of 160 ppm, and exhibited a good stability and excellent linearity.