To provide a sluice gate capable of maintaining watertightness while preventing a gap from being generated due to deflection deformation without increasing the board thickness of the door of the sluice gate.

The sluice gate is provided with a backing plate formed with an opening, the door thereof, which allows the above opening to be opened/ closed, a lifting means for moving up and down the above door, and an urging means for pressing the above door against the backing plate for the purpose of enabling the control of the opening/closing and closing-off of the above opening. In the sluice gate, there are installed reinforcing members for preventing the occurrence of the deflection deformation in the above door during the closing-off of the above door in such a manner as to be coupled to the respective surfaces of the vertical upper end, central part and lower end of the above door. The sluice gate is characteristically constituted so as to transfer pressing force from the central part to the upper and lower ends.