The removal of Manganese ions with biogenic-Fe precipitate by iron-oxidizing bacteria and the effect of NaOH addition on Mn ion removal in the ecperiment was investigated. In both experiments with and without NaOH addition, manganese ions were removed by co-precipitation with Fe precipitate such as jarosite, and the amount of removed Mn increased with increasing initial Fe concentration, and the removal ratio of Mn was about 4~14%. The effect of NaOH addition was no significant, and the co-precipitation method would be effective for the removal of small amount of Mn.