To provide a composition for pest controlling microsporidia of seafood, high in effects on prevention of infections of microsporidia to muscle or organs of seafood, inhibition of growth thereof, or extermination thereof and excellent in safety, and a pest controlling method of microsporidia of seafood using the same.SOLUTION: There is provided a composition for pest controlling microsporidia of seafood for preventing infections of microsporidia belonging to Microsporidium genus to muscle or organs of seafood belonging to order Perciformes or order Pleuronectidae, for inhibiting growth of the microsporidia or for exterminating the microsporidia, the composition containing one or a plurality of a group consisting of compounds such as fenbendazole, albendazol, triclabendazole, and a pharmaceutically acceptable salts thereof as active ingredients, excluding a medicine bath agent.SELECTED DRAWING: None【課題】魚介類の筋肉又は臓器への微胞子虫の感染の予防、増殖の抑制、又は駆除する効果が高く、安全性にも優れた魚介類の微胞子虫の防除用組成物及びそれを用いた魚介類の微胞子虫の防除方法の提供。【解決手段】スズキ目又はカレイ目に属する魚介類の筋肉又は臓器へのMicrosporidium属に属する微胞子虫の感染の予防、微胞子虫の増殖の抑制、又は微胞子虫を駆除するための魚介類の微胞子虫の防除用組成物であって、フェンベンダゾール、アルベンダゾール、トリクラベンダゾール等の化合物及びその薬学的に許容される塩からなる群より選択される１又は複数を有効成分として含む魚介類の微胞子虫の防除用組成物（薬浴剤を除く。）。【選択図】なし
