PURPOSE: To obtain an exhaust valve which can open and close an optional exhaust valve port among low and high pressure ones, and does not discharge water with a simple structure.

CONSTITUTION: An inflow port 1, a valve chamber 5, and an exhaust port 3 are formed by valve casings 2, 4, 6. A valve seat member 11 on which a communication port 12 are opened for communicating the valve chamber 5 with the exhaust port 3 is arranged on the valve casing 4. A cylindrical exhaust valve body 13 is slidably arranged inside the communication port 12. A float 21 is provided on a lower side of the exhaust valve body 13. The upper side of the valve body 13 is slidably arranged inside a port 19 formed on the valve casing 4. A through-hole 15 is formed inside the exhaust valve body 13 for the communication of the valve chamber 5 and the port 19, respectively through a port 16 and a port 20. A cylindrical wall 17 is arranged around the port 16. An exhaust valve port 23 is communicated with the exhaust port 3 of an exhaust valve body 9.