In a vent control valve for a fuel tank, a housing receiving a float assembly therein is provided with a communication hole passed across a wall of the housing, and an opening of the communication hole facing an interior of the housing is directly exposed to an interior of the housing when the float assembly is in a low position and overlaps with a peripheral wall of the float assembly when the float assembly is in a high position. By suitably selecting the size of the communication hole and/or the number thereof, a desired delay in the dropping of the liquid fuel level in the housing following the filling up of the fuel tank can be achieved. Thereby, overfilling of the fuel tank can be avoided.