A projection type displaying apparatus with a movable built-in screen has an image display, an image projector and a position detector for detecting a position where the built-in screen is installed. When the position detector determines that the built-in screen is in an image projection pass, the focus of the image projector is adjusted on the built-in screen and the image projector projects the image onto the built-in screen. When the position detector determines that the built-in screen is out of the image projection pass, the focus of the image projector is adjusted on an external screen and the image projector automatically projects the image onto the external screen.