To provide a retaining device capable of preventing a fall accident of a pipe joint and to provide the pipe joint using the retaining device.

A retaining device 6 used for a pipe joint 2 of a wavy pipe 1 includes a first retaining fixture 7. The first retaining fixture 7 has a ring-shaped part (71). The ring-shaped part (71) is arranged between waves P1 of the wavy pipe on the inside of the wavy pipe 1. The pipe joint 2 includes a nut 3, a socket 4 and the retaining device 6. The nut 3 is attached to an outer circumference of the wavy pipe 1. The socket 4 is connected with the nut 3. The retaining device 6 is arranged between the nut 3 and the socket 4.