The Jiji Weir () is a weir located in Nantou County, Taiwan. The weir is located at the border of Jiji Township, Lugu Township and Zhushan Township. It is currently the biggest weir in Taiwan.
The construction of the weir started in July 1990, and was completed in December 2001.
The weir features the Taiwan Water Museum () within Jiji Township border.
The weir is accessible southwest of Jiji station of Taiwan Railway.