Route 163 was designated on 18 May 1953 from Osaka to Yokkaichi. On 1 April 1963 the section from Iga to Yokkaichi was redesignated as a portion of Route 25.
References
^"一般国道の路線別、都道府県別道路現況" [Road statistics by General National Highway route and prefecture] (PDF) (in Japanese). Ministry of Land, Infrastructure, Transport and Tourism. Retrieved 19 February 2020.