To reduce the construction cost by surely performing drainage in a construction job site of an underground structure.

A drainage box 1 is formed by a drum part 2 for installing an underwater pump 5 and a cylindrical part 3 provided on the upper part of the drum part. A water stopping member 17 can be stuck to the periphery of the cylindrical part, and a form 18 can be provided to surround the water stopping member. The cylindrical part 3 is provided with an upper opening 4 for getting the underwater pump in and out, and the drum part 2 is provided with a plurality of water-conveyance ports 6 connected to a guide channel for guiding underground water to a shallow sump. The water-conveyance ports are provided with a stop cock 8 to be opened and closed. Accordingly, the shallow sump can easily be installed, leakage of underground water can be completely prevented, and the underwater pump can be recovered.