A heat-insulating container is used for an instant dried food and is excellent in heat-insulating property, design and economy. The container comprises a paper cup body with a bottom, which has an inner surface coated with a polyolefin resin and is provided with an outward curled portion formed at an upper opening end of the cup body and at least one horizontal rib formed on a side wall of the cup body so as to project outward therefrom; and an inverse-frustoconical paper sleeve provided with an inward curled portion formed at a lower end of the sleeve. The cup body and the sleeve are integrally combined with each other so that an upper end of the sleeve is joined to an outer periphery of the side wall of the cup body, which is adjacent to the outward curled portion of the cup body, and an inner surface of the inward curled portion of the sleeve is joined to an outer periphery of a lower portion of the side wall of the cup body.