When a province was divided to be owned by several feudal lords, each lord was allowed to have one castle (for example, Ozu-jo Castle, Matsuyama-jo Castle and Uwajima-jo Castle in Iyo Province, etc.), and when a clan of feudal lord owned territory across a few provinces, they were allowed to have one in one province (for example, Tsu-jo Castle [Ise Province] and Ueno-jo Castle [Iga Province] of the Tsu Domain).
一つの令制国を複数の大名で分割して領有している場合は各大名ごとに一城とし（例伊予国の大洲城、松山城(伊予国)、宇和島城等）、一つの大名家が複数の令制国にまたがって領有している場合は各令制国ごとに一城とした（例津藩の津城（伊勢国）、上野城（伊賀国））。