PROBLEM TO BE SOLVED: To provide a water stopping structure that prevents water leakage from a space between a floor through which a cable tray vertically extended is penetrated and the cable tray to a floor below.SOLUTION: On a floor 7 in a water stopping structure 1 that prevents water leakage from a space between the floor 7 through which a cable tray 5, which stores a cable therein and is vertically extended, is penetrated and the cable tray 5 to a floor below, a curve 9 is arranged around the cable tray 5 separately from the cable tray 5; a first board 17 is arranged above the curve 9 so as to cover the periphery of the cable tray 5 separately from the curve 9; a first sheet metal 19 is arranged so as to cover the periphery of the first board 17; a back up material 21 is arranged between a lower end of the first board 17 and the curve 9; a polyurea 23 is sprayed to cover the first sheet metal 19, the backup material 21, the curve 9 and the floor 7; and a second board 25 is arranged to cover the polyurea
