Josaku is a historical term for a government office with defending facilities that was located to govern the north part of present-day Niigata Prefecture and the Tohoku region under the ritsuryo system during the ancient Japan.
城柵（じょうさく）とは古代日本の律令制下、現代の新潟県北部及び東北地方を支配下に治めるために設置した防御施設を備えた官衙を指す歴史学用語。