Regeneration of the natural zeolite adsorbed by NH4+ by use of saturated sodium chloride solution was examined. The following results were obtained.1) The regeneration rate of zeolite was not dependent on their place of occurrence and crystal structures.An empirical formula to predict regeneration rate by the particle size and the solution temperature was obtaind.2) The space velocity of saturated sodium chloride solution in the regeneration column was determind in order to make the retention time in the column equal to the regeneration time given by the obtained empirical formula.The volume of the regeneration solution used to obtain 90% regeneration ratio was 1.7ml · meq-1 for Clinoptilolite and 0.8ml · meq-1 for Mordenite regardless of NH4+ exchange capacity.3) The regeneration solution was reused after NH4+ was removed. The regeneration capacity of the reused solution was almost the same as the new solution although K+, Ca++ and Mg++ accumulated in the solution. The sodium chloride used treat one cubic meter of the model wast water by the presented process was 104 grams for Clinoptilolite and 81 grams for Mordenite.