Floating flap gate

The present invention aims to reduce the manufacturing precision and assembling precision of a door body while simplifying the structure of a frame of the door body, so as to reduce the manufacturing work load. This invention discloses a floating flap gate (1) installed at a road surface (rs) at an entrance of a building or an underground space. A support part installed at a proximal side of a door body (4) and in a vertically swinging status is constituted by a bottom metal member (5) installed at a proximal part (4a) of the door body (4), a resin plate (6) supporting the door body (4) while the door body (4) being in a vertical status, a waterproof membrane (13) covering the bottom metal member (5) and the resin plate (6), a first press plate (14) installed at the portion of the waterproof membrane (13) covering the bottom metal member (5), and a second press plate (16) installed at the portion of the waterproof membrane (13) covering the resin plate (6). The width of the bottom metal member (5) is the same