PURPOSE: To attain the weight reduction and miniaturization of a gate by providing a gate consisting of a skin plate bent into an arch-shaped curved face toward the upstream side, slidably movale parts to be provided to straight facing sides of the skin plate, and a tension member to connect between the straight facing sides.

CONSTITUTION: A gate consists of a skin plate 1 bent into an arch-shaped curve face toward the upstream side, slidably movable parts 4 as supporters to be provided to straight facing sides of the plate 1, and a round bar 21 as a tension member to be provided between the straight facing sides of the plate 1. In place of the round bar 21, a crescentic beam 22 may be used for holding the curved face of the plate 1, and a reinforcement 3 may also be provided as needed. Since the gate has the arch-shaped curved face protruded toward the side to be subjected to water pressures, little moment acts on the plate 1, and therefore, the thickness of the plate 1 can be made smaller and the weight and size of the gate can be reduced because the beam 22 used is one having strength high enough to withstand tension.