An air mattress including a plurality of air cell groups including air cell groups corresponding to the back area, the buttock area and the thigh area of a person lying on the air mattress, each of which groups being made of a plurality of air cells, the air cells group corresponding to the back area and the thigh area including a lower section and a upper section, the upper section being stacked on the lower section, an air supply/release pump, and an air tube connecting the air cell groups corresponding to the back area and the thigh area to the air supply/release pump and connecting the air cell group corresponding to the buttock area to the air supply/release pump in an independent system for each other.
