There is provided: a CPU that, in at least one case among a case in which fluctuation of a fixed interval in the acquired parallax amount is greater than a predetermined value, and a case in which the parallax amount reaches a predetermined allowed limit value, or a case in which an object of acquisition of the parallax amount can no longer be detected, judges that there is an abnormality in the parallax amount, and that, in a case that is none of these, judges that there is no abnormality in the parallax amount, and that, when it is judged that there is no abnormality in the parallax amount, carries out first parallax adjustment, and that, when it is judged that there is an abnormality in the parallax amount, switches to control of a second parallax adjustment and carries out parallax adjustment.