| Country: | TWN |
| Type: | PH |
| Route: | 84 |
| Established: | July 1998 |
| Alternate Name: | 北門玉井線 (Beimen-Yujing Expressway) |
| Length Km: | 41.428 |
| Map: | TW_PHW84route.svg |
| Direction A: | West |
| Terminus A: | in Beimen, Tainan City |
| Junction: | in Xiaying, Tainan City in Guantian, Tainan City |
| Direction B: | East |
| Terminus B: | in Yujing, Tainan City |
| Previous Type: | PH |
| Previous Route: | 82 |
| Next Type: | PH |
| Next Route: | 86 |
Provincial Highway 84 is an expressway, which begins in Beimen, Tainan on the Provincial Highway No. 61 and ends in Yujing, Tainan on Zhongshan Road (Provincial Highway No. 20).
The route between Beimen, Tainan and Syuejia, Tainan is under construction and will be completed in 2014.
A short section in Beimen, Tainan between National Highway No. 61 and Provincial Highway No. 17 was open in 2004. It functions as a feeder to National Highway No. 61.
The total length is 41.428 km.
The entire route is within Tainan City.