To cut off a construction work tunnel from an operation tunnel in an underground disposal facility in which the construction work tunnel and the operation tunnel cross each other, and to enable a boring shear to be carried out and materials to be carried in by using the construction work tunnel.

In a disposal facility where a construction work tunnel 4 for carrying construction materials and a boring shear and an operation tunnel 5 for carrying in waste from a ground facility cross each other, a solid crossing part 41 is provided by expanding the construction work tunnel 4 at a crossing part 50 where the construction work tunnel 4 and the operation tunnel 5 cross each other, and detours the operation tunnel and cutoff doors 52, 53 are provided for cutting off the construction work tunnel 4 from the operation tunnel 5. Therefore, the operation tunnel 5 is cut off from the construction work tunnel 4 and the construction work tunnel 4 is used to carry out the boring shear and carry in the materials, on the other hand.