To provide a tube device which has a sealing structure, and has a few components, and is inexpensive, compact, and highly reliable without using metallic connecting members, such as a tie rod, a through bolt, an O-ring.

A fluorocarbon resin casing 1 comprises a fluorocarbon resin tube 4 surrounding the outer periphery of a fluid tube 3, a fluorocarbon resin lid member 5 which has a receiving portion 8 for receiving the terminal of the tube 4 and at least one sealing surface 10 provided in the receiving portion and a connecting portion 29 to other piping 28, a fluorocarbon resin union nut 6 which is fitted on the terminal of the tube 4 and is screwed into one end of the lid member 5, and at least one seal member 19 formed by bringing the terminal of the tube 4 into close contact with the seal surface 10 of the lid member 5 through pushing the tube 4 from outside through fastening the union nut 6 to one end of the lid member 5.