In a balance exercise machine, a swing mechanism swings a seat with composition of a swing motion in an anteroposterior direction and a swing motion in a widthwise direction. The swing motion of the seat in the anteroposterior direction is driven faster than, preferably twice as fast, as that in the widthwise direction. The origin of the swing motion of the seat in the widthwise direction is discrepant from origin of the swing motion of the seat in the anteroposterior direction within a half-cycle.