An auto focusing device for a camera includes a focus detecting section which detects a focused state of an image taking lens an AF mode setting section sets an AF mode of the camera to either a first AF mode or a second AF mode. An auxiliary light emitting section emits an auxiliary light to the object in association with the focus detecting operation by the focus detecting section if the object has a low luminance. An emission control section limits the number of times that the auxiliary light emitting section emits the auxiliary light to the object to one per a predetermined number of operations by the focus detecting section if the AF mode setting section has set the AF mode to the second AF mode.