Exit is the bottleneck of an evacuation from a room and the flow rate through an exit is believed to be depended on its width. A series of experiments were conducted in a bi-dimensional container where mice were driven to pass through two kinds of exit of the identical width, i.e., a conventional exit and a hopper-shape exit. The evacuation efficiency of the two exits was experimentally compared by using mice under competition. The results showed that a hopper-shape exit reduces the escape time by 25% compared with a conventional exit. Further study was conducted with the presence of a column in front of the two exits. The presence of a column in front of the conventional exit increases the escape time by 22.5%. On the contrary, the placement of column in front of the hopper-shape exit reduces the escape time by 48%. The study showed that the escape efficiency could be greatly improved by appropriately redesigning configuration of exit.