Changhua County (Mandarin Pinyin: Zhānghuà Xiàn; Wade-Giles: Chang¹-hua⁴ Hsien⁴; Hokkien POJ: Chiang-hòa-koān or Chiong-hòa-koān) is the smallest county on the main island of Taiwan by area, and the fourth smallest in the country.

In 1723, after the Zhu Yigui rebellion, an inspector official in Taiwan requested to the Qing Emperor to designate Changhua to another county magistrate and legal warden because of the increasing population in the northern part of Zhuluo County.

[4] During early Japanese rule, the island was subdivided into three ken (県): Taihoku, Taiwan, and Tainan.

[5] Changhua county is located on the west coast of Taiwan, bordering Taichung City on the north separated by Dadu River, so Changhua County and Taichung City are often referred to as the Taichung–Changhua metropolitan area.

The current Magistrate of Changhua County is Wang Huei-mei of the Kuomintang.

Changhua County, an electoral bellwether, is seen as a political battleground between the Kuomintang (KMT) and the Democratic Progressive Party (DPP).

While it has historically favored the KMT, recent elections have swung in the direction of the DPP.

Lukang used to be the economic hub of central Taiwan in its early years where it was a commercially prosperous area.

In August 2016, the Changhua County Government signed an agreement with Canada's Northland Power and Singapore's Yushan Energy to develop "Hai Long", a 1,200 MW-capacity offshore wind generation project spread over 2,300 km2 (890 sq mi) off the coast of the county.

[15] Changhua was one of the cultural centers of Taiwan, with a lot of ancient monuments and structures left from the Qing Dynasty, including the Confucian Temple, Tian Ho Gung, built in Lukang in 1647.

Historical buildings in the county are the Changhua Wude Hall, Daodong Tutorial Academy, Fuxing Barn, Lukang Ai Gate, Lukang Kinmen Hall, Lukang Rimao Hang, Luocuo Church, Spring of Youth, Yi Yuan Mansion and Yusan Hall.

Changhau has one professional basketball team, the Formosa Taishin Dreamers of the P. League+ (shared with Taichung).