The regeneration of baked volcanic ash soil by removal of adsotbed PO4-P with acid and alkali solutions was investigated. Almost 100% Of PO4-P adsorbed on baked volcanic ash soil was removed by treatment with H2SO4 solution of pH 0.5 and NaOH solution of pH 12. HCl solution of pH 0. 5 removed only about 60% Of PO4-P. On repeated regeneration with H2SO4 solution of pH 1.0, the M-P adsorption capacity of baked volcanic ash soil was retained well up to the fourth regeneration. The adsorption capacity decreases to about 15% of initial value when NaOH solution of pH 12 was used. It is concluded that H2SO4 solution is suitable for the regeneration of baked volcanic ash soil by removal of adsorbed PO4-P.