To provide a flop gate with earth rejecting function which can prevent the deposition of earth below the downstream-side surface of a door body without being affected by the gradient of a river.

A flap gate is installed to the river bed of a river across the river and constituted in a freely flapping state through a torque shaft provided near the river bed. At the time of installing the gate, the flapping door body 4 of the gate is housed in a due section 5 formed by digging the river bed and, at the same time, a covering means 9 which covers the dug section 5 is provided so that an inclined surface while descends toward the downstream side from the downstream-side surface of the door body 4 may be formed when the door body 4 is erected.