Provided is an air mattress in which internal pressure can be controlled according to the movements of a bed. The air mattress is provided with a plurality of air cell groups lined up in the lengthwise direction of the air mattress, each of which groups is made from a plurality of bladder-shaped cells； an air supply/release pump； and an air tube connecting the air cell groups and the air supply/release pump in an independent system for each air cell group of two or more air cell groups out of said air cell groups. Air supply/release by the air supply/release pump to each of the air cell groups is controlled by a controller, at least a part of information needed to control the bed is received from an external sensor for detecting such information, and air supply/release by the air supply/release pump for each of the air cell groups is controlled on the basis of the received information.
