The objective of this study was to analyze the factors affecting on fuel consumption of agricultural tractor. According to the statistical analysis, fuel consumption of agricultural tractor was considerably influenced by kind of operation, throttle engine speed and gear steps of tractor but much less by kind of soil. Specific fuel consumption of the tractor in plowing, dry paddy tilling, wet paddy tilling and wet paddy levelling was 0.33~0.36, 0.30~0.45, 0.19~0.34, 0.28~0.39 L/$kW{cdot}h$, respectively, and $CO_2$ emission was 0.36~0.45, 0.35~0.58, 0.22~0.42, 0.24~0.37 kg/$kW{cdot}h$, respectively. Specific fuel consumption and $CO_2$ emission increased as throttle engine speed increased but reversely proportional with gear step of tractor, by which one can reduce fuel consumption and $CO_2$ emission with practicing of "Gear up & Throttle Down" technique in paddy operations.