A vehicular air supply system includes: a first air operation mechanism which is operated at an air pressure of a first pressure value or less; a second air operation mechanism which is operated at an air pressure of a second pressure value or less, the second pressure value being lower than the first pressure value; a compressed air generator which generates compressed air to be supplied to the first air operation mechanism and the second air operation mechanism; and a first discharge air supply unit which supplies air discharged from the first air operation mechanism to the second air operation mechanism when a pressure value of the air discharged from the first air operation mechanism is higher than a pressure value of the air supplied from the compressed air generator to the second air operation mechanism.