A magnification change-over device is arranged to be highly suitable for a camera of the kind having a photo-taking lens and a viewfinder arranged independently of each other. The device includes the photo-taking lens having an image magnification which is variable; the viewfinder which is arranged to have an image magnification thereof also variable; an operating device for varying the image magnification of the viewfinder; a detecting device for detecting the magnifying state of the viewfinder; and a driving apparatus for driving the photo-taking lens according to a detection signal of the detecting device when a shutter release operation is performed. After a magnification setting operation is performed on the viewfinder, the change-over device changes the magnification of the photo-taking lens according to the magnification of the viewfinder when a photographing operation is actually performed.