PURPOSE: To obatin the bubble tube which is hard to be damaged in assembling and handling, by manufacturing upper and lower divided bodies having flanges at their peripheral parts in order to form a bent tube having an injecting port by using synthetic resin, performing bonding at the flanges, injecting alcohol and the like, and sealing the port.

CONSTITUTION: The bent tube 1 has end plates 2 and 3 at both ends and the liquid injecting port 4 in the end plate 2. The divided bodies 5 and 6 are obtained by dividing the tube into halves in the axial direction. The flanges 7 and 10 are provided at the edges of the divided bodies, and the divided bodies are bonded by the edges. The bent tube 1 is formed by acrylic resin and the like. The divided bodies are bonded, by combining the flanges 7 and 10, and by the high frequency heating, at the part of a protruded stripe 8 provided at the central part of the flange 7. The alcohol and the like 14 are injected through the injecting port 4. Thereafter a cap body 11 is inserted to the port 4, and a flange 13 of the cap body 13 is hermetically sealed and bonded by using a bonding agent. Even though the tube is dropped, it is not broken like glass and danger is not caused by the crushed pieces thereof.