PURPOSE: To improve heat insulation capacity while improving watertightness.

CONSTITUTION: Metal interior frame materials 4 are connected together in a square frame shape, and thereby an interior frame body 1a is made up. Rubber exterior frame materials 5 are connected together in a square frame shape, and thereby an exterior frame body 1b is made up. The interior frame body 1a and the exterior frame body 1b are connected together, and a frame body 1 is made up with an inward-looking dent 19 provided, surrounding four sides. The peripheral edge of a panel 3 is made to face the inward-looking dent 19 that surrounds four sides, and a horizontal piece 14 of the exterior frame material 5 is pressed against the exterior surface 3a of the panel 3, and watertightness is ensured therewith.