Abstract: A noiseproof vent valve for a fuel tank is provided. A damping member installed in the vent valve has at least two elastic pieces, preferably the four elastic pieces. The movement of the float is absorbed by elastic deformation of the elastic pieces, and thus the float is prevented from coming into contact with a lower end forming the bottom of a valve body. However excessively the float fluctuates, no “clicking” contact noise occurs at the vent valve. As a result, the merchantability of a hybrid vehicle sensitive to low noise can be greatly increased.