Ppharmaceutical agents and food products which have no side effects, are easy to ingest continuously, and have a serum triglyceride-lowering effect are provided. A lipid metabolism-ameliorating agent and a serum triglyceride-lowering agent, each comprising as an active ingredient a culture of a bacterium belonging to the genus Bacillus , are disclosed. The bacterium belonging to the genus Bacillus is preferably Bacillus subtilis , and more preferably Bacillus subtilis C-3102 (FERM BP-1096). The lipid metabolism-ameliorating agent and the serum triglyceride-lowering agent are useful for treating and preventing diseases such as arteriosclerosis.
