A double pipe includes an outer pipe in which an inner pipe is placed, and a spacer that maintains a clearance between the inner pipe and the outer pipe. At least a part of the spacer is press-fitted by an inner circumferential surface of the outer pipe and an outer circumferential surface of the inner pipe. More specifically, the outer pipe includes a diameter-reduced portion having undergone diameter reduction by plasticity processing. An inner circumferential surface of the diameter-reduced portion is present across the entire circumference other than the opening of the spacer, and presses an outer circumferential surface of the spacer inwardly in the radial direction.