An illumination apparatus which is capable of appropriately determining whether or not a radiating direction of a flash is deviated from a direction targeted by a user and preventing degradation in user convenience. The illumination apparatus has a movable unit that has a light-emitting unit, and a main body unit that holds the movable unit rotatably in a predetermined direction. A present angle of the movable unit with respect to the main body unit is detected, and a difference between the present angle and a target angle to which the movable unit is to be moved is obtained. When the difference is smaller than a threshold value, it is determined that there is no angular deviation of the movable unit. The threshold value used in the determination varies with the target angle.