To improve the degree of freedom of a relative position for a rail for a member for retaining the rail that is connected to a piping trestle or the like.

Piping trestles 10 are installed toward the extension direction of a refrigerant pipe 2 for an air-conditioning device. The piping trestles 10 are connected by a connection rail 40. A rail insertion space is formed at a rail retention member 20 for constituting one portion of the piping trestles 10. By enabling the relative position of the connection rail 40 in the rail insertion space to be variable, the connection position of the piping trestles 10 for the connection rail 40 can be set arbitrarily.