A seat with a ventilation system that maintains seated person's coolness by blowing air to minimum segments of a seatback and a seat cushion so that seated person's comfort is maintained is provided. Air-blowing means is controlled in air-blowing quantity and air-blowing time periodically by air-blowing control means, and air blowing in each period is set to include a first term T1 in which a predetermined quantity of air is blown and a second term T2 in which the predetermined quantity of air to be blown is gradually reduced.
