This thin air jack is provided with: an airtight body (2) that is formed, from a film, in a bag shape having a sealed structure; an air supply hose (4) that has a base end inserted into the airtight body (2) in an airtight fashion and is provided, at a tip end, with a connector (3) having a non-return valve, said connector (3) being connected to an air supply source; a hose (6) having a valve mounted thereto, said hose having a base end inserted into the airtight body (2) in an airtight fashion and being provided, at a tip end, with a safety valve (5); a cover body (7) that is formed in a bag shape from a synthetic resin material and accommodates the airtight body (2) with the tip ends of the hoses (4, 6) protruding outward; an interior body (8) that is formed in a bag shape from a synthetic fiber woven fabric and accommodates the airtight body, etc. (2, 7) with the tip ends of the hoses (4, 6) protruding outward; and a cylindrical exterior body (9) that is formed by turning a hose with the same structure as a fire hose inside out, or a cylindrical exterior body (9) that is obtained by coating a cylindrical woven fabric. The exterior body (9) accommodates the airtight body, etc. (2, 7, 8) with at least the tip end portions of the connector (3) having a non-return valve and the safety valve (5) protruding outward from one end of the exterior body (9), and is formed in a flat bag shape with both ends closed.