To prevent damages to an inner pipe and an outer pipe caused by a temperature change.

The double layer pipe 10 is provided with the inner pipe 11 having a socket 13 for connecting pipes at the end part and the outer pipe to cover the surrounding of the inner pipe 11, and the inner pipe 11 and the outer pipe are formed by materials having different thermal expansion rates. The double layer pipe has a first outer pipe 30 to cover the tip of the socket 13 and a second outer pipe 40 to cover the part excluding the tip of the socket 13 around the inner pipe 11, the first outer pipe 30 is connected to the socket 13 and the second outer pipe 40 is held in a state relatively displaceable in the axial direction to the inner pipe 11. Therefore, even if the thermal expansion rates of the inner pipe 11 and the outer pipe are different, a difference of expansion/shrinkage between the inner pipe 11 and the outer pipe caused by the temperature change can be absorbed.