In order to develop gas sensor operating at low temperature, thick film $Co_{3}O_{4}$ sensor was fabricated. $Co_{3}O_{4}$ powder was prepared by precipitation from cobalt nitrate solution and the powders containing ethylene glycol as a binder was screen-printed on alumina substrate. Characteristics of sensitivity, response time, and recovery were investigated in terms of binder content and heat treating conditions. The $Co_{3}O_{4}$ sensor contained 15% ethylene glycol and heat-treated at $300^{circ}C$ for 24hr showed the highest sensitivity at the operating temperature of $250^{circ}C$. Its sensitivity of 1.1 to 5000ppm butane gas was very high, as compared with $0.8{sim}0.85$ at the operating temperature of $350{sim}400^{circ}C$ for a commercial $SnO_{2}$ gas sensor. It is found that response time was fast, but recovery was poor for the sensor.