Abstract: A baby bottle with an air valve device has a bottle, an air valve device and a cap. The bottle has a mouth. The air valve device is a check valve and has a valve seat mounted on the mouth of the bottle and having at least one through hole, a valve stem and a valve disk. The valve seat has at least one through hole. The valve stem is mounted slidably through the valve seat and has a bottom end. The valve disk is attached to the bottom end of the valve stem and has an air chamber and an annular disk. The air chamber is hollow and has a proximal end attached to the bottom end of the valve stem. The annular disk is formed around and protrudes out from the proximal end of the air chamber and selectively closes the through hole in the valve seat.