In an air mattress (1) including a plurality of levels of air mattress layers (5, 7) which are vertically stacked, in each of the levels of air mattress layers (5, 7), flexible hollow air cells (43, 23) each extending along the width of the air mattress (1) are arranged in parallel with each other in the longitudinal direction of the air mattress (1), air cells (43, 23) in each of the upper air mattress layer (7) and the lower air mattress layer (5) are divided into a plurality of groups such that the air cells (43, 23) are expanded or contracted in units of the groups by supplying or discharging air to/from these air cells (43, 23).提供一種患者長期橫躺在床上等時,能確實防止患者發生褥瘡之氣墊。係在具有上下方向疊層有複數層之氣墊層5、7的氣墊中,複數層的氣墊層5、7的各層是由在氣墊1的短邊方向延伸的撓性中空氣室43、23在上述氣墊1的長邊方向並列構成,在複數層的氣墊層的上層氣墊層7及下層氣墊層5的各層中的氣室43、23,被分為複分組,藉由上述分組分別輪流進行供氣及排氣,使其得以依各分組組別進行膨脹、收縮。1‧‧‧氣墊3‧‧‧基墊層5、7‧‧‧氣墊層17‧‧‧撓性中空氣室(基墊層)20、33、35、53、55‧‧‧連結口23、43‧‧‧撓性中空氣室(氣墊層)61‧‧‧空氣幫浦63、65、67、69、71‧‧‧充氣管
