A vehicle brake system (1), which can reduce influence of failure in a barometric pressure detection mechanism on the basis of controlling the barometric pressure to be optimum, including: an atmospheric pressure sensor (9); a negative pressure booster (2); a negative pressure pump (8); a master power pressure sensor (2a) that detects booster pressure; an activation determining unit (72a) that compares an activation threshold value PthON that has larger negative pressure as the atmospheric pressure increases with a determination value calculated based on the booster pressure to determine activation of the negative pressure pump; and a deactivation determining unit (72b) that compares a deactivation threshold value PthOFF that has larger negative pressure as the atmospheric pressure increases with the determination value to determine deactivation of the negative pressure pump, wherein the activation threshold value PthON is set to have maximum negative pressure of activation which negative pressure is for a high-pressure boundary value paH of the atmospheric pressure, and the deactivation threshold value PthOFF is set to have minimum negative pressure of deactivation which negative pressure is for a low-pressure boundary value paL of the atmospheric pressure.