PURPOSE: To obtain an adhering method for an air box of a test apparatus of a side wall of a building which enables the sealing of a sample accurately by a press fitting over the entire perimeter of the sample without the deformation of a seal plate and an air box.

CONSTITUTION: In adhering method for an air box of a test apparatus for the performance of a side wall of a building, a sample mounting member 2 is provided to fix a side wall material 6 to be tested. The sample mounting member 2 is made up of a front member 3 to fix a plane part of a wide wall and bending members 4 and 5 which are provided by being bending at least at one end part of the front member 3 to fix a side wall material for a corner part of the building to at least at one end of the front member 3. A mobile air box 55 is mounted to form an airtight space in front of the sample covering the front of the sample in a sealed manner and a sealing part 56 on the side of the air box is sealed on a sealing part 54 provided in the periphery of the sample by a press fitting. The air box 55 is moved from the slant direction to the plane part of the sample to press fit the sealing part 56 on the side of the air box with respect to the sealing part 54 on the side of the sample.