that in the method according to the present invention the water impermeable supporting member average supply quantity of water jet streams in a direction of width on said supporting member ejection pressure and the hardness of surface of said supporting member are extremely important in this example a random web with weight of about 40 g m 2 consisting of a rayon staple fiber with fineness of 15 denier and with fiber length of 51 mm is guided into the apparatus of the type as shown in fig5 for jet treatment and thereafter subjected to drying at a normal temperature room temperature property of the sample obtained in this way is shown in table 1 the diameter of jet hole of the nozzle in the apparatus referred to above was 0 12 mm in order to obtain a comparative sample said fibrous web was guided onto an endless belt which works as a water permeable supporting member and which consists of a wire gauge with wire diameter of 0 046 mm and with mesh of 20 and treatment was made by said nozzle in the same manner as mentioned above the sample obtained in this way was found to be of openings additional experiment was carried out under the condition that the nozzle 20a shown in fig5 is closed and the fibrous web is subjected to treatment in the same manner as mentioned above without preliminary treatment on the belt 16 the result was that the fibrous web was damaged by drainage in the space between the rolls 17a and 18 and.