A protective cover for motor vehicle mainly includes a cover, at least two flexible metal rings that are lengthwise sequentially spaced at and attached to an inner side of the cover to enclose a relatively large area of the cover, and adjustable belts with hook belt fasteners spaced at a lower edge of the cover. The flexible metal rings are adapted to automatically stretch the cover for covering an upper part of a motor vehicle, and the hook belt fasteners are adapted to firmly hold the cover to a lower part of the motor vehicle. To fold and store the cover, simply fold the cover to align the metal rings with each other, and bend the aligned metal rings into several superposed smaller loops, so that the folded cover may be stored in a bag in the flat and folded state to occupy only a relatively small space.