To provide an exhaust valve capable of opening/closing a valve port with a large opening area over low pressures to high pressures.

In this exhaust valve, an inlet 4, a valve chamber 3, and an outlet 11 are formed by a casing comprising a body 1, a bottom cover 2, and a valve seat member 9. An upper valve port 12 and a lower valve port 13 with the same opening area are formed in a valve seat member 9 on a vertically same axis where the valve chamber 3 is allowed to communicate with the outlet 11. A lower valve body 21 opening/closing the lower valve port 13 is disposed in the valve chamber 3 on the lower side of the lower valve port 12, and an upper valve body 15 opening/closing he upper valve port 12 is disposed on the outlet 11 side between the upper valve port 12 and the lower valve port 13. A guide bar 22 is formed integrally with the lower surface of the guide bar 22, and a float 14 is connected to the lower end of the guide bar 22. A lower guide bar 17 is formed integrally with the lower surface of the upper valve body 15. When the lower valve body 21 is seated on the lower valve port 13 and the upper valve body 15 is seated on the upper valve port 12, the lower end face of the lower guide bar 17 is brought into contact with the upper end face of the lower valve body 21.