We have found that putting an obstacle in front of an exit increases the pedestrian outflow through an exit in an evacuation situation from our experiments. In this paper, conflicts and turning, which affects the pedestrian out-flow significantly, is studied in detail to analyze the effect of an obstacle. In the floor field model, which is a pedestrian dynamics model using cellular automata, conflicts are taken into account by the frictional parameter, which is not sufficiently realistic, and turning is neglected. Therefore, we have improved the frictional parameter to the frictional function, which is more realistic than the frictional parameter, and introduced the turning function, which represents the decrease in walking speeds when pedestrians turn. The frictional and the turning function clearly explain the mechanism of the effect of the obstacle, i.e., the obstacle blocks a pedestrian moving to the exit and decreases the average number of pedestrians involved in the conflict. © 2009 SICE.