PURPOSE: To provide a connecting device which can easily and highly sealed, by providing a pipe and port formed in the pipe, by hermetically fixing the port and the pipe so that the port quickly receives a tubular inlet or outlet of a member which is to be connected.

CONSTITUTION: A connecting pipe for connecting a member in a fluid circuit, comprises a pipe 2, and a port 3 attached to one end of the pipe 2. Two seal rings 9, 10 which are separated from each other by a washer 11 are located in a cavity 7 in a sheath 4 having a cylindrical tip end part in the port 3. Further, a bushing 12 is fixed in a cavity 8, and a flexible annular clamping member 13 incorporating a plurality of pawls is slidably located in the cavity 8. The cavity of the bushing 12 has a part whose diameter is changed so as to compress the pawls of the clamping member 13 on a pipe 14 fitted in the port 3. As a result, it is possible to prevent occurrence of insufficient connection of the pipes and leakage, and to prevent the fluid passage from being constricted in the connection point.