PURPOSE: To reduce the allowance of wrapping between the front plate of a cover unit by a method wherein a projected part is provided on the back surface of the end of the front plate, which is wrapped by the cover unit, while an engaging unit, engaging elastically with the projected part of the front plate, is provided on a rib provided so as to pinch the front plate between a decorative body projectingly toward the direction of the cover unit.

CONSTITUTION: The lower rim of a front plate 14 is positioned so as to be inserted between a cover unit 16 and a rib 17 so as to be pinched between the cover unit 16 since the back surface of the same is pushed by an abutting part 17a formed on the rib 17. A cut-and-raised projection 14a is provided on the back surface of the front plate 14 while an engaging part 18, engaging elastically with the projection 14a, is provided projectingly on the rib 17 of the decorative frame body 15. The projected part 14a is provided so as to be contracted with the end 14a of the front plate 14 whereby a dimension (a) may be nulified. The aggravation of appearance of a door 12 due to a sink in thickness may be prevented while the thickness of the cover unit 16 may be thinned at the same time.