To provide a ventilating system 6 for preventing the gathering of odor of rooms 2 around a shared space 3, and reducing the installation cost and the operation cost.

This ventilating system 6 having a fan unit 7 for supplying and exhausting the air, is mounted in a building 1 having the plurality of rooms 2 such as a living room 4, a toilet 5 (or bathroom) and the like, and the shared space 3. The outside air of the building 1 is absorbed by the air supply fan of the fan unit 7, and collectively supplied to a supply port 9 formed on a ceiling of the shared space 3, and the air in the living room 4 is exhausted to the external of the building 1 by an exhaust fan of the fan unit 7 from an exhaust port 8 without passing through the shaped space 3. The air in the toilet 5 is ventilated by a ventilating fan 14 for local ventilation.