A method for the manufacture of moisture absorbing fiber having high whiteness, characterized in that an acrylic fiber comprising acrylonitrile polymer where a (meth)acrylate compound as a copolymer component is less than 5% by weight is subjected to crosslink introduction treatment using a hydrazine compound, to hydrolysis and to reducing treatment. A method for the manufacture of moisture absorbing fiber having high whiteness, characterized in that (1) acrylic fiber comprising acrylonitrile copolymer where a (meth) acrylate compound as a copolymer component is less than 5% by weight is treated with a hydrazine compound whereby introduction of crosslink and increase in nitrogen content to an extent of 1.0 &tilde& 10.0% by weight is carried out, (2) treatment with an aqueous solution of alkaline metal salt is carried out whereby carboxyl group of a metal salt type by which CN group is hydrolyzed is produced in an amount of 4.0 &tilde& 10.0 meq/g and (3) a reducing treatment by a reduction treatment agent selected from a group consisting of hydrosulfite, thiosulfate, sulfite, nitrite, thiourea dioxide, ascorbate and hydrazine compound is carried out.