To enable a device to remove liquid to the outside of a system when the liquid can not be forcedly fed.

In a sealed vessel 2, an operating fluid introding/discharge ports 11, 13 and a forced feed liquid inflow/discharge ports 16, 17 are provided. In the sealed vessel 2, a float 3 and a supply/discharge air valve 4 are housed. To the forced feed liquid inflow port 16, an inflow side check valve 6 is connected, to the forced feed liquid discharge port 17, a discharge side check valve 9 is connected. In the discharge side check valve 9, an inlet 65, out-system discharge port 66 and an outlet 67 are provided, a switch valve unit 69, interrupting the out-system discharge port 66 switched to a position communicating the inlet 65 and the outlet 68 and a position communicating the inlet 65 and the out-system discharge port 66, and a check valve element 76, permitting a flow in the outlet 67 from the sealed vessel 2 and stopping a flow in a reverse direction thereof, are housed. When a liquid forced feeder 1 causes a trouble, the switch valve element 69 is turn operated, the inlet 65 and the out-system discharge port 66 are communicated, liquid is removed to outside the system from the out-system discharge port 66.