Abstract: The vehicle has a fuel vapor releasing device, a brake booster, a negative pressure pump, and a pump suction passage which puts the fuel vapor releasing device, the constant pressure chamber and a suction port of the negative pressure pump in communication. The vehicle also has an air intake passage in communication and a brake negative pressure control valve which switches selectively between communication of the suction port with the constant pressure chamber and disconnection of the communication. When the negative pressure pump is actuated to produce a negative pressure which is supplied to the constant pressure chamber of the brake booster, on condition that a suction pressure of the pump suction passage is equal to or lower than a booster pressure of the constant pressure chamber, the brake negative pressure control valve is opened.