Threshing force is the force required to detach the grains from the bundle of panicles during a threshing operation. For successful design of any threshing equipment, the knowledge of grain detachment force is essential. Therefore, this study was undertaken to determine the grain detachment force of paddy. The grain detachment force of six varieties of paddy, i.e., Lalat, Pratibha, Birupa, Pratikshya, Sidhanta, and Hasanta was determined using Universal Testing Machine. The grain detachment force of single grain was measured at three positions, i.e., lower, middle, and upper of panicles for each selected variety at four grain moisture content at 100 mm per min of test speed. The grain detachment force for the whole panicle of each variety was also determined at four speed (50, 100, 150 and 200 mm per min) and at four levels of moisture content. The highest grain detachment force was observed at the lower portion and the lowest at the upper portion of panicles for all the selected paddy varieties at all levels of grain moisture content. The detachment force decreased with decrease in grain moisture content for all the varieties. Grain detachment force decreased as the test speed increased from 50 to 150 mm/min but increased at 200 mm/min for all the varieties. The maximum detachment force was observed at the lower position of panicle at 17.8% moisture content for Sidhanta variety.