To provide an attachment fixture for easily attaching/detaching a lid body, reliably latching the lid body, and attaching the lid body to an inspection opening so as to be attachable/detachable when the attachment fixture is held on either side, i.e., a back board side or a lid body side, and to provide a method for attaching/detaching the lid body through the use of the attachment fixture.

The attachment fixture of the lid body for closing the inspection opening which is formed in a board body includes: a base board; a lock repulsive part extended from one end part of the base board to the surface side; and a pinch repulsive part which is extended from the other end part of the base board to a back surface side and formed in a substantially recessed shape. A step piece part whose width dimension is a little larger than the thickness dimension of a lid board is provided with elasticity in a vertical direction and formed in the termination part of the lock repulsive part. The pinch repulsive part of each attachment fixture is fitted and locked to the opposite peripheral edge parts of the inspection opening. One edge part of the lid body is locked to the step piece part of the lock repulsive part in one attachment fixture, and then, the lid board is pressurized. The other edge part of the lid body is fitted and locked to the step piece part of the lock repulsive part in the other attachment fixture.