Abstract: A liquid containing a hydrophilic polymer is applied by spreading or impregnation to a porous sheet comprising paper or a nonwoven fabric containing not less than 30% by weight and not more than 100% by weight of hydrophilic fiber to provide a hydrophilic polymer-processed sheet of which the surface and/or the interior of the porous sheet is filled with the hydrophilic polymer, which is made insoluble to water. This sheet is used as a sheet for a total heat exchanger which has higher conductivity of sensible heat and latent heat than conventional sheet for a total heat exchanger that uses a moisture permeable membrane.