明治12(1879)年に郡区町村編制法が兵庫県で施行され行政区画として発足した明石郡は全域が旧明石藩領で、明治22(1889)年の時点で明石町、林崎村、大久保村、魚住村、伊川谷村、玉津村、櫨谷村、押部谷村、平野村、神出村、岩岡村、垂水村の1町11村でした。
相生町には明石郡の警察署、電信局、治安違罪裁判所、郡役場、公会堂など次々と移転新築され、郡の一大官庁街となりました。
相生町は、この地域の先進地であった明石城下と大蔵谷村の中間点であり、民家も比較的に密集していなかったことで移築や新築が容易であったことが推測されます。
郡制には郡長（官選）と郡会・郡参事会が設けられ自治体として機能しておりましたが、町の単位、県の単位も存在していたため、行政区分が煩雑でした。やがて各村は併合を繰り返し、明石市、神戸市などに統合され、郡制は大正12(1923)年に廃止されました。
明石市の初代市長は明石郡最後の郡長の三輪伸一郎氏で、彼は明石市の理想は庭園的住宅都市の建設であると述べていました。
Trivia 3 government office area of Akashi County
After the Formation of County, Ward, Town and Village Law was enforced in Hyogo Prefecture in 1879, Akashi County started as the administration block contained territory of the old Akashi domain at that point in 1889, one Town of Akashi and 11 Villages of Hayashisaki, Okubo, Uozumi, Ikawadani, Tmatsu, Hazetani, Oshibedani, Hirano, Kande, Iwaoka also Tarumi. After government offices of Akashi County such as the police station, the telegraph station, the Public Order Violation Court, the County Office and the Public Hall were moved or built at Aioi-cho, the first class government office area of the County appeared there. We estimate that it was easy to bring and reconstruct or construct buildings because Aioi-cho was located at the halfway point between the advanced area of the castle town and Okuradani Village also houses were not so close together. County system had the head of County, the County committee and the County council, so it functioned as the municipality but coordination with administration of town and prefecture was difficult. After frequent annexations, each of villages integrated with Akashi City, Kobe City and son on. The county system was abolished in 1923. Miwa Shinichiro who was the last head of Akashi County and the first Mayor of Akashi City said that the ideal of Akashi City was the establishment of the garden city.
明石ヘリテージマップ『人丸』2018
