A control device for an automatic transmission includes a parking lock mechanism configured to lock/unlock rotation of a power transmission shaft by setting a parking rod at locked/unlocked position when the automatic transmission is in a parking range or in other ranges, a parking drive mechanism configured to set the parking rod at the unlocked position by supplying hydraulic pressure, a hydraulic pressure control valve configured to intercept the hydraulic pressure supply to the parking drive mechanism when power is supplied thereto, and supply the pressure when power is not supplied thereto, a regulating mechanism configured to regulate the movement of the parking rod at the locked position, and a controller configured to, when the parking rod is at the locked position, maintain supply of power to the valve, while an engine speed is higher than a given value, after power of a vehicle is turned OFF.