The Former Mountain line (Chinese: 舊山線; pinyin: Jiù Shānxiàn; Pe̍h-ōe-jī: Kū Soaⁿ-soàⁿ) is a railway branch line in Taiwan operated by the Taiwan Railways Administration. The name literally means "old Mountain line" (another name for the Taichung line) and can refer to any section of the Taichung line that ceased operations when it was replaced by a newer rail. However, the term is most widely used to refer to the segment between Sanyi and Houli stations.