Abstract: A vent valve includes a main valve having a valve chamber provided therein with an inside annular valve seat and an outside annular valve seat, a valve body normally seated on the seats under its own weight and opened by atmospheric pressure in response to negative pressure, a water collecting groove formed outward of the outside annular valve seat, a connecting cylindrical part provided at a position deviating from an axis of the valve chamber for communicating with the valve chamber, and a communicating flow path formed along the axial direction of the valve chamber for allowing communication between the water collecting groove and an interior of the connecting cylindrical part.