PURPOSE: To provide a connecting structure for a ribbed pipe, wherein any groove by which turbulent flow is generated in fluid is not formed on the inner surface of the connecting part.

CONSTITUTION: A socket 1 provided with a taper part 11 on the innermost part is formed on the end of one ribbed pipe P, and an insertion port 2 wherein a ring-like packing 3 is attached between annular ribs (r) is formed on the end of the other ribbed pipe P. And, in the connecting structure of the ribbed pipe P wherein the socket 1 and the insertion port 2 are fitted to each other, the annular rib (r) positioned in the endmost part and a rib bent part 21 wherein the end of the rib (r) positioned next thereto is bent are formed on the top end of the insertion port 2, and this rib bent part 21 is inserted until it is close attached to the inside of the taper part 11 of socket 1.