PURPOSE: To prevent the leakage of liquid by interposing a compression coil spring between a connection body inner side end face and an insert unit end face, in the case of a hose connecting device comprising a connection body, insert unit, O ring, union nut and a sleeve.

CONSTITUTION: A cylindrical connection body 3 with its outside threaded, having a connector in the one end part and a fitting part 43 in an inside in the other end part, is provided, and an inert unit 4, having in its one end part a tapered part 41, is fitted to the fitting part 43 of the connection body 3. The insert unit 4 is fixed to the connection body 3 by a union nut 7 while providing an O ring 5 in the fitting part of the connection body 3 to the insert unit. By screwing the union nut 7, a hose 1 is pressed to the insert unit 4 by a sleeve 6. Further a compression rubber 8 is interposed between internal end faces of the connection body 3 and the insert unit 4. As a result, fluid can be prevented from its leak even with unevenness in the thickness of the hose.