PURPOSE: To secure airtightness by using a screw cover, improve design in a thin type, and improve easiness of handling.

CONSTITUTION: Respective rear parts of a vessel body 1 to which an intermediate cover 4 is screw-fitted and on which an annular wall 5 housing a decorative pan 10 is erected and in which an intermediate frame 3 to define a housing recessed place 6 is fitted and a cover body 2 having a through hole 7 through which an upper part of the intermediate cover 4 penetratingly passes and in which a lower part of the intermediate cover 4 can be fitted, are hinged, and a midway part of an outer peripheral surface of the intermediate cover 4 is formed as a large diameter part 9 to prevent slipping-out to the outside of the cover body 2 from the through hole 7.