PURPOSE: To provide a method for producing a super water-absorbing fiber having a good curd permeability and water-insoluble by carboxymethylating a cellulose fiber and subjecting it to crosslinking treatment by using a specific compound in a non-swelling solvent.

CONSTITUTION: This method comprises carboxymethylating a cellulose fiber (pref. regenerated cellulose) in the ratio of 1 to 3.5 mol/kg by using monochloroacetic acid, and treating it in a non-swelling solvent (pref. an aliphatic alcohol) of the carboxymethylcellulose by using a compound of the formula ((n) is 2 to 7) for crosslinking the vicinity of the surface of the fiber into high density. The resultant fiber is insoluble and super absorbing, adapted to sufficiently swell when absorbing water and broadly applicable to sanitary materials and agricultural uses.