A conventional baby seat is a curved frame having a seat portion and a backrest portion which integrally extends from the seat portion, a retaining bar removably connected between two sides of the backrest portion so as to retain the baby in the baby seat.  A foam pad with a fabric enclosing the pad is put on the surface of the seat portion and the backrest portion of the baby seat so that the baby or kid sitting in the seat may feel comfortable.  However, for the baby seat, there has no ventilation device to ventilate the seat itself and the baby or kid is retained in the seat so that he/she could feel uncomfortable especially when the car is exposed under the sunshine with all the doors and windows closed.  If the baby or kid in the baby seat feels uncomfortable, the baby or kid will cry and this affects the concentration of the driver. 
The present invention intends to provide a baby seat used in a car wherein the seat has a ventilation device connected thereto, a plurality of apertures defined through the casing of the hollow seat frame so that air flows via the apertures and the heat between the body of the baby or kid is dispensed by the air flow.  The present invention has arisen to mitigate and/or obviate the disadvantages of the conventional baby seat.