PROBLEM TO BE SOLVED: To provide favorable electric continuity while securing gas-tightness between respective members in piping, and facilitate manufacturing and assembling of the respective members.SOLUTION: The piping structure includes a first conductive tube member 14 connected by engagement to an endoscope housing 9 by means of engagement parts 9e and 14f, a second conductive tube 16 mounted on the first tube member 14, and an O-ring 17 to maintain gas-tightness between the first tube member 14 and the second tube 16. Between the first tube member 14 and a flange projection 18 of the second tube 16, a spring washer (conductive cushioning member) 20 is provided to achieve electric continuity for securing continuity between both. Instead of providing the spring washer 20, the O-ring 17 may be a conductive O-ring.
