A total of 28 species belonging to 16 genera in 4 subfamilies was collected in 4 parks of the ruins of castles located in Shikoku, western Japan. In Tokushi- ma-chuo Park (Tokushima Prefecture), the most ant species (22) were collected. Of the 28 species collect- ed in this study, Pheidole fervens and Ph. indica were alien ant species. The dominant ant species measured by the frequency of occurrence at the honey baits was Pristmirmex punctatus in Dogo Park, Tetramorium tsushimae in Tamamo Park (Kagawa Prefecture), Ph. noda in Kochi Park (Kochi Prefecture) and Tokushi- ma-chuo-Park. The similarity of species composition calculated by Nomura-Simpson’s Coefficient (NSC) was the greatest (0.93) between Tamamo Park and Tokushima-chuo Park.