Biomss adsorbent which is a kind of activated carbon was successfully prepared from biomass. The walnut shells were used as a raw material for the production of activated carbon. Preparation process involves the roasting . Chemical activation was carried out by using NaOH as an activation agent at 700℃, 2hr. N2-BET surface areas of activated walnut shells char prepared by chemical activation were measured as about 283~968m2/g. The adsorbate transmittance of Phenol was determined UV absorption at 740nm as maximum absorption wavelength using UV spectrophotometer. Removal of Phenol in solution by activated carbon was carried out and structural change of pore surface was observed by SEM.