To provide a water level adjusting gate allowing a door body to be rapidly lifted/lowered with small force and stably lifted/lowered over a long period of time.

Winches 14A, 14B are mounted to the upper left and right sides of a square frame 1, and lower ends of wires 16 wound around the winches 14A, 14B are connected to the left and right upper parts of the door body 4 to hang the door body 4. The left and right side edges of the door body 4 are slidably inserted in guide grooves 3 of left and right column parts 2, 2 of U-shape of the frame 1. A rotating shaft 18 of the left and right winches 14A, 14B is connected, and a hand handle 19 mounted to one winch 14A is rotated to simultaneously rotate winding drums 15A, 15B of the left and right winches 14A, 14B, thus lifting/lowering the door body 4.