The present invention is intended to provide a reducing agent effective for color development of meat and uses therefor. The present invention provides a reducing agent containing a heme reductase derived from a microorganism belonging to the genus Bacillus. Preferably, crushed bacterial cells of Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus natto, Bacillus thuringiensis, or Bacillus mycoides are used.