Abstract: A cap for vent nozzles comprises a main cap part turnably mountable on a lower nozzle member to adjust a passage through the vent nozzle, the main cap part having an inlet opening formed to communicate with an ambient atmosphere and allow air to come into the lower nozzle member and then into an interior of a device to be vented, an auxiliary cap part connected with the main cap part and provided with a passage and an outlet opening communicating with the passage, the auxiliary part being formed so that it is fittable on the main cap part so that in a fitted condition the passage communicates with the inlet opening of the main cap part and the outlet opening of the auxiliary cap part faces toward an interior of the vent nozzle in a direction opposite to the inlet opening of the main cap part.