PROBLEM TO BE SOLVED: To ensure that belts run on accurate tracks around guide rollers in an area of a pressure zone in which the belts pressurize a material to be treated in cooperation with each other.SOLUTION: A device 10 includes an endless belt structure 11, is configured to circulate around a route to which a guide roller structure 13 is incorporated and defines an elongate sheet movable along the route 12. Separable connection is performed along the longitudinal edge of the elongate sheet. While the belt structure is moved, a tubular structure 21 is continuously assembled at one end and is continuously disassembled at the other end of the tubular structure. Part of the tubular structure has liquid penetration. The device 10 includes a belt part 15. Two endless rope elements connected to the belt part support the belt. By each roller structure, the rope element is supported on the guide roller structure. The device includes a means for compressing the tubular structure along a portion thereof, and energizes the rope elements outwardly to separate them from each other at a section where the tubular structure is compressed.