Abstract: Described herein is a floating flap gate including a gate leaf having a buoyancy forming portion, the gate leaf being configured to be raised due to buoyancy effect (e.g., from water), a bottom fitting mounted to a proximal end portion of the gate leaf, the bottom fitting having a convex circular arc-shaped surface across a width direction of the gate leaf, a plate member having a concave circular arc-shaped surface to be mated with the convex circular arc-shaped surface of the bottom fitting when the gate leaf is in a lowered state, wherein the concave circular arc-shaped surface is in contact with the convex circular arc-shaped surface when the gate leaf is raised.

Abstract: In order to structurally simplify a frame that is a component of a door body and to reduce required levels of manufacturing precision and assembly precision, thereby reducing a manufacturing man-hour, provided is a floating flap gate 1 installed on a road surface rs at an entrance portion of a building or an underground space. An upward swinging support portion is composed of a bottom fitting 5, a resin plate 6 configured to support a door body 4 when the door body 4 is raised, a water cut-off film 13 covering the bottom fitting 5 and the resin plate 6, a first pressing plate 14, and a second pressing plate 16. The bottom fitting 5 has a convex circular arc-shaped surface 5a. The resin plate 6 has a concave circular arc-shaped surface 6a to be mated with the convex circular arc-shaped surface 5a of the bottom fitting 5.