To provide an exhaust valve wherein a holding part can positively catch a float at valve opening wherein the float is seated on a valve seat.

A valve chamber 3 with an inflow port 4 opened in a lower part and an outflow port 5 opened in an upper part is formed by a casing comprising a body 1 and a lid 2. The valve seat 6 is formed between the valve chamber 3 and the outflow port 5. The float 12 is disposed in the valve chamber 3 in a free state. The holding part 13 catching the float 12 at valve opening wherein the float 12 is seated on the valve seat 6 is provided in the outflow port 5. The holding part 13 is formed as a different part from the valve seat 6. A coil spring 16 is provided to advance the holding part 13 in a float 12 side. By floating of the float 12, the holding part 13 is retreated to seat the float 12 on the valve seat 6 and carry out valve opening.