Provided is an air mattress capable of preventing the occurrence of decubitus ulcers in a person lying on the air mattress.The air mattress has a plurality of air cell groups made from a plurality of bladder-shaped cells and lined up with respect to the lengthwise direction of the air mattress so as to support at least a head area, shoulder area, back area, buttock, thigh area, knee area, and heel area of a person lying on said air mattress an air supply/release pump and an air tube connecting said bladder-shaped cells and said air supply/release pump in one or a plurality of independent first systems for each of the air cell groups out of said air cell groups and one or a plurality of independent second systems for each of specific bladder-shaped cells out of the plurality of air cell groups. Air supply/release by the air supply/release pump is controlled by a controller, and the pressure in at least air cell groups corresponding to a back area and a thigh area is greater than the pressure in an air cell groups corresponding to a buttock area.
