An air-sealed body capable of automatically opening an air valve is provided. First, the two inner films are laminated between two outer films. An air passage and a plurality of air columns are formed through joining by means of heat-sealing. Air inlets are formed by heat-sealing in the two inner films at the places where the heat-resisting material is coated, and a plurality of heat-sealed blocks are formed through joining by means of heat-sealing at the sides of the air inlets. When air is filled in, the two outer films of the air passage are pulled open outward in a longitudinal direction, the air passage contracts in a lateral direction due to a drop height of the heat-sealed blocks. The two inner films are squeezed by the heat-sealed blocks to be pulled open outward in the longitudinal direction to open the air inlet.