Thanks for the reply 
However, using SetFocus is difficult because there is nothing to look at in the direction I want the AI to rotate.
The function I want to create now is that when a horse runs towards the AI and the collision in front of the horse overlaps, AI rotates to the left and right of the horse and then excute montage that jump forward.
It is difficult to assign an Actor to SetFocus because it is not possible to specify something that is always visible on the left and right sides of the horse.