To prevent erosion on an inner wall of an exit passage by fluid at a maximum use pressure or higher exhausted from a second valve port.

A trap chamber 14 and the exit passage 15 are formed in trap casings 1, 2, 3, 6 and 8 having an entrance 5 and an exit 7. A valve seat 18 having a valve port 17 that communicates the trap chamber 14 with the exit passage 15 is provided, and a float 22 releasing from and seating on the valve seat 18 to open and close a valve port 17 is disposed in the trap chamber 14. A second valve seat 26 having a second valve port 25 that communicates the trap chamber 14 with the exit 7 is provided, and a valve member 28 releasing from and seating on the second valve seat 26 to open and close the second valve port 25 is disposed in the exit 7 side of the second valve port 25. The valve member 28 is biased in a direction of closing the valve by a coil spring 31 disposed between the member and a spring bearing 30. The center axis of the second valve port 25 is formed coaxially with the center axis of the exit 7. An exit side end of the second valve seat 26 is opened in the exit 7 to which an exit pipe 32 is connected.