$SnO_{2}$-based thick film ethanol gas sensors were fabricated on alumina substrates and their ethanol gas sensing characteristics were investigated. The film sintered at $400^{circ}C$ for 2 hrs. showed the highest sensitivity to ethanol gas and the sensitivity of the film to 1000 ppm ethanol gas in air was 97 % at an operating temperature of $250^{circ}C$. The addition of $Fe_{2}O_{3}$ to $SnO_{2}$ enhanced the sensitivity by changing the type and number of surface acidic/basic sites.