To provide a novel food composition for activating butyric acid production bacteria, and a butyric acid production bacteria activator.SOLUTION: There are provided a food composition for activating butyric acid production bacteria, and a butyric acid production bacteria activator, containing Euglena as an active ingredient and used for increasing occupancy of butyric acid production bacteria in intestinal flora. There is provided a food composition for activating butyric acid production bacteria, in which the butyric acid production bacteria are bacteria belonging to Clostridium leptum or Faecalibacterium prausnitzii. There is provided a butyric acid production bacteria activator, containing Euglena as the active ingredient and used for increasing occupancy of butyric acid production bacteria in intestinal flora.SELECTED DRAWING: Figure 1【課題】新規な酪酸産生菌賦活用食品組成物及び酪酸産生菌賦活剤の提供。【解決手段】ユーグレナを有効成分として含有し、腸内フローラにおける酪酸産生菌の占有率を増加させるために用いられることを特徴とする酪酸産生菌賦活用食品組成物及び酪酸産生菌賦活剤。酪酸産生菌がクロストリジウム・レプタム群に属する菌、あるいは、フィーカリバクテリウム・プラウスニッツィ菌である酪酸産生菌賦活用食品組成物。ユーグレナを有効成分として含有し、腸内フローラにおける酪酸産生菌の占有率を増加させるために用いられることを特徴とする酪酸産生菌賦活剤。【選択図】図1