A novel generation method of optically active 1,2-diols with excellent optical purity (>98% enantiomeric excess) from their racemates was developed using the resting cells of Alcaligenes sp. DS-S-7G. This method was based on microbial enantioselective oxidation of the racemic 1,2-diols. When 1% (v/v) 1,2-butanediol was used as a substrate, the degradation reaction in the presence of NAD(+) could be carried out 8 times within 200 h.