To provide an air mat which will not warp back even though part of either air layer is pressed and recessed, to ensure that the stable condition is kept, and which is free from risk that no air exists in the recessed part.

An air mat concerned is composed of an upper air layer and a lower air layer, which are isolated from each other by a partitioning sheet 3 and welded to the sheet 3 with a certain spacing reserved in between so that a plurality of crests and bottoms are formed. The welding lines 4, 5 should be different between the upper and lower air layers.