noun
1955 System
Historical term for Japan's post-1955 political structure, with the LDP as the ruling party and the JSP as the main opposition, lasting until 1993.
See also: 自由民主党 (じゆうみんしゅとう) · 日本社会党 (にっぽんしゃかいとう)
５５年体制は１９９３年に崩壊した。
The 1955 System collapsed in 1993.
戦後日本の政治は長らく５５年体制のもとにあった。
Postwar Japanese politics was long under the 1955 System.
The JSP was the main opposition party during the 1955 System.
From 1955 (the year the system was established) + 体制 (system, structure).