To provide an exhaust valve having a simple structure and functions of both an initial quick exhaust valve and an automatic exhaust valve.

A valve chamber 3 is formed inside with a casing consisting of a body 1 and a top lid 2. An inlet 4 is formed at a lower part of the valve chamber 3 and an outlet 5 is formed at an upper part thereof. A large valve port 6, which communicates the valve chamber 3 with the outlet 5, is formed on the top of the valve chamber 3. A main float 7, which has a cross section in an approximately inverted recessed shape and opens and closes the large valve port 6, is guided and disposed vertically in the valve chamber 3. A small valve port 8 is formed at the top wall of the main float 7 so as to vertically penetrate therethrough. A spherical sub-float 9, which opens and closes the small valve port 8, is disposed in the main float 7.