To prevent rainwater flowing over the outer surface of a sump from flowing to the wall surface of a building by providing a bottom surface below a main body that is approximately in the form of a short cylinder, and projecting the peripheral surface of the short cylinder downward from the bottom surface for formation of a draining suspended part.

An almost rectangular sump A is attached to the wall surface D of a building, and a drain pipe B and an elbow C are inserted from an inlet 19 in the sump A. A water chute 16 is suspended from the bottom surface 15 of the sump A, and a downspout E is connected to the water chute 16. The lower ends of the front 1, side 11, and back 12 of the sump A are extended downward from the bottom surface 15 to form a draining suspended part 15, the end of the suspended part 15 being curved upward to form a turn 18. Rainwater flowing along the outer surface of the sump can, therefore, be prevent from flowing to and polluting the wall surface of the building.