| Koshiji | |
| Native Name Lang: | ja |
| Settlement Type: | Former municipality |
| Seal Type: | Emblem |
| Pushpin Map Caption: | Location in Japan |
| Subdivision Type: | Country |
| Subdivision Name: | Japan |
| Subdivision Type1: | Region |
| Subdivision Name1: | Hokuriku |
| Subdivision Type2: | Prefecture |
| Subdivision Name2: | Niigata Prefecture |
| Subdivision Type3: | District |
| Extinct Title: | Merged |
| Extinct Date: | April 1, 2005 (now part of Nagaoka) |
| Leader Title: | Mayor |
| Leader Title1: | Vice Mayor |
| Unit Pref: | Metric |
| Area Total Km2: | 58.44 |
| Population Total: | 14,160 |
| Population As Of: | 2003 |
| Timezone1: | JST |
| Utc Offset1: | +09:00 |
| Blank Name Sec1: | City hall address |
was a town located in Santō District, Niigata Prefecture, Japan.
As of 2003, the town had an estimated population of 14,160 and a density of 242.30 persons per km2. The total area was 58.44 km2.
On April 1, 2005, Koshiji, along with the town of Oguni (from Kariwa District), the village of Yamakoshi (from Koshi District), the town of Nakanoshima (from Minamikanbara District), and the town of Mishima (also from Santō District), was merged into the expanded city of Nagaoka.[1] [2]
Echigo Kotsu Nagaoka Line (until 1975)
JNR Uonuma Line (until 1984)