To provide a floating land lock gate in which increase of construction materials or deterioration of natural scenery can be avoided, a response of a door body in inflow of seawater or the like is quickened, and impulse with a door body closing operation can also be reduced.

In a floating land lock gate 100, on a bottom face 11a of a land lock opening 11 formed by providing a land lock wall body 21 in an embankment 20, a door body 10 which generates buoyancy in water is mounted through a hinge member 12 to freely rise and fall and in order to prevent water leakage between a side edge 10a of the door body 10 and an inner side face 11b of the land lock opening 11, a side face water-tight member 13 is provided additionally on the inner side face 11b of the land lock opening 11. Within a virtual fan-shaped area 13 drawn on the inner side face 11b of the land lock opening 11 by the side edge 10a of the door body 10 when the door body 10 rises/falls, the side face water-tight member 14 is provided in an area which is closer to the hinge member 12 and narrower than the virtual fan-shaped area 13.