Seal device for tubular member

A seal device is constituted of a plurality of seal tubes. After a connected-tube body having base members disposed at a fore end and a rear end is inserted into a fluid passage such as a tubular member, the seal tubes are expanded by injecting gaseous nitrogen into each of the seal tubes. The intermediate portions of the seal tubes along a longitudinal direction are press-fitted to the inner surface of the fluid passage over the entire circumference thereof, whereby the fluid passage is sealed. Since the connected-tube body is easily bent in the vicinity of a connecting base member between the tubes, the connected-tube body can be easily curved along the fluid passage, thus facilitating an operation for inserting the connected-tube body into the fluid passage and also enhancing a sealing property with respect to the fluid passage.