In the design of sulfate reducing bacteria (SRB) bioreactors to remove metal ions from acid mine drainage, the tolerance of bacteria to metal ions is an important factor. The present study investigated the effects of Mn²⁺ concentration on the growth and Mn removal activity of SRB in mediums containing 100∼600 g·m⁻³ Mn²⁺. The Mn²⁺ adsorbed on SRB cells and weakened the ability of bacterial sulfate reduction. However, the suppressive effect of Mn²⁺ on SRB growth can be disregarded, and 200 g·m⁻³ of Mn²⁺ in solution was removed, satisfying the requirement of the maximum contaminant level (MCL) of environmental water quality in Japan.