To fill air at a short time, and house an air mat and an equipment in an injector main body in an unused time by detachably arranging a cover body on the upper part of the air injector main body for filling air in a rubber boat and the like, and stretching a fabric body having good air tightness between the cover body and a bottom member.

In the case where a large boat and the like are inflated, a cover body 10 and an opening part frame part 12 are locked with each other in a tightly closed condition by a holder 11, the connector 19 of a hose 13 is connected to an air feed port such as a rubber boat, an injector main body 1 is vertically moved, and air is fed. At this time, in the case where the injector main body l is pushed downward and air is fed to a hose 13 side, a small hole 15 is closed by the non-adhesive part of a diaphragm valve, and thereby, air leakage is prevented. When the injector main body 1 is pulled upward, outside air is sucked from the small hole 15 into the injector main body l., Since the injector main body 1 is formed largely, it is possible to house a held rubber boat, a beach mat, an equipment, and the like into the injector main body 1 by dismounting the cover body 10.