A check joint structure for a connection of an air nozzle of a tire and a connection hose of an air compressor, the air compressor contains: a box, a sealant supply can, and a connection hose. The box includes a body of the air compressor. The sealant supply can includes an open segment and a supply tube. The connection hose includes a first segment and a second segment. The second segment has a check connector which includes a fitting sleeve, and the fitting sleeve has a threaded orifice, a through orifice, and a projected shoulder. A cylindrical base includes a cylindrical room, a stepped coupling segment, a conduit, and a first stepped portion. A first spring is received into the cylindrical room to abut against the first stepped portion. A valve bolt includes a contacting element, at least one cutout, a head, a conical rib, and a neck.