To form a thermal insulation/airtight inspection hole excellent in execution efficiency and workability, facilitating handling, having an insulating property and airtightness, excellent in durability and capable of reducing a product cost and an operation cost.

The inspection hole is constituted by fitting a cover 7 in each outside frame 2 having openings formed in a floor, a wall or the ceiling. A frame panel 3 is combined with each outside frame 2, and a thermal insulating material 8 fitted in the frame panel 3 is fixed to the rear side of the cover 7. Thus, the cover 7 is combined with the thermal insulating material 8 in advance, the outside frame 2 is combined with the frame panel 3 to enable them to be handled as one component, so that construction work can be simplified at a site, and attachment/detachment work to the cover 7, the outside frame 2 of the thermal insulating material 8 and the inside of the frame panel 3 is facilitated.