PURPOSE: To prepare activated carbon fiber having absorptivity of creatine, urea, etc., and useful for the purification and regeneration of the dialyzate solution of an artificial kidney, by immobilizing urease to the surface of a carrier composed of activated carbon fiber.

CONSTITUTION: Cellulosic fiber or polyacrylonitrile fiber is carbonized at high temperature, and activated with steam to obtain activated carbon fiber carrier. Urease is immobilized to the carrier by the combined use of adsorption and crosslinking, or by forming covalent bonds. The form of the activated carbon may be felt, cut fiber, or sheet, however, felt is preferable in view of the handleability. The urease used in the process may be the one originated from bacteria, molds, leguminous plants, etc., however, sword bean-originated urease is most excellent in view of the availability and the stability.