Kudoa septempunctata is the causative agent of a foodborne disease associated with the consumption of raw Paralichthys olivaceus (olive flounder). Chickens were used to establish specific antibodies against K. septempunctata spores. A specific antiserum, CS#3, raised against sonicated spores, also recognized intact spores. The CS#3 antiserum showed high titers for sonicated and intact K. septempunctata spores and was suitable for both ELISA and immunohistochemical staining. Using homogenated raw olive flounder meat, the ELISA system detected more than 5.0×10(5) spores in 1 g of tissue, which was consistent with the number determined by microscopic examination. The preparation of rapid detection kits for K. septempunctata spores in P. olivaceus muscle tissue using immunochromatography with CS#3 antiserum should be useful for preventing the foodborne disease in the field.