The object of the present invention is to provide an excellent total heat exchanging element paper and a total heat exchanging element which are excellent in heat transferability, water vapor permeability and gas barrier properties and cause no mixing of supplied air and discharged air. The present invention provides a total heat exchanging element paper using a paper made using mainly a natural pulp beaten to a Canadian modification freeness of not more than 150 ml, a substantially non-porous total heat exchanging element paper comprising a substantially non-porous cellulosic base which contains a moisture absorbing agent, a non-porous total heat exchanging element paper having a high gas barrier property which has a thickness of not more than 100 μm and a carbon dioxide permeation constant specified in JIS K7126 of not more than 5.0×10−13 mol·m/m2·s·Pa, and a non-porous total heat exchanging element paper having a high enthalpy exchangeability which has a water vapor permeability specified in JIS Z0208 of not less than 1000 g/m2·24 Hr at 20° C. and 65% RH.