The Dadu River, also called the Wu River, is a major river in the Northwest of Taiwan. It is the sixth-longest river on the island with a total length of .
The Dadu River is named after a former port near its mouth, now the Dadu District of Taichung.
It is also known as the , a calque of its Hokkien name. The same name appears in English as the the pinyin romanization of its Mandarin pronunciation. It received the name from the many black-winged birds that used to live along the river.
It flows through Taichung City, Changhua County, and Nantou County for . It is the 6th-longest river on Taiwan Island and the 4th-largest in drainage area.