To provide an air valve capable of preventing the outflow of liquid even if an exhaust hole is left in a completely nonclosable state by influence of an impurity such as refuse.

This air valve has a valve casing 5 having a connecting part to a pipe in a lower part, and having a valve seat 4 for forming the exhaust hole 3 in an upper part, a valve element 6 for opening-closing the exhaust hole 3, and a float 11 arranged inside the valve casing, and pressing the valve element 6 in the closing direction by buoyancy. A splash shelter 15 having an air vent 15a is arranged under the valve element 6. An auxiliary float 20 for opening-closing the air vent 15a is arranged just under the splash shelter 15.