To easily adjust pressure according to variation in overflow amount without providing any complicated controller on a pressure source side by providing a branch pipe which communicates with a guide-in pipe, making part of a pressure-fed fluid body overflow to the branch pipe, and controlling the pressure of the fluid body supplied to a tubular body.

The guide-in pipe 3 is arranged intruding into the tubular body 1 from its opening part. The branch pipe 4 is connected to the guide-in pipe 4 nearby its entrance side 3B, and this branch pipe 4 is fitted with a manometer 5 and an adjusting means 6 for a valve, etc. When the fluid body is pressurized and fed to the guide-in pipe 3, the pressure of the fluid body operates on the branch pipe 4 and is always measured by the manometer 5. When it is decided that the pressure is higher than a specific value, the adjusting means 6 is properly opened to discharge part of the fluid body, thereby properly correcting the pressure in the guide-in pipe 3. Therefore, the guide-in pressure of the fluid body charged in the internal space 2 can be adjusted only by the adjusting means 6 without controlling the pressure on the supply device side.