The removal of manganese from artificial wastewater has been studied using agricultural waste biomass such corncobs as the adsorbent. The adsorption experiments were carried out by column method to eliminate heavy metal ion under the optimum condition. The concentrations of heavy metal in the sample were determined atomic absorption spectrophotometrically and calculate the average adsorption efficiency. From the experiment, it was found that the average adsorption efficiency of manganese which has concentration of 50,100 and 150 ppm are 74.11%, 66.94% and 62.68%, respectively. In addition, the corncobs can be a potential adsorbent for removing other heavy metal such copper, lead, cadmium, zinc and nickel. In case of interfering metal, manganese affect the adsorption of cadmium, zinc and nickel by corncobs.