| Junji Koizumi 小泉 淳嗣 | |
| Fullname: | Junji Koizumi |
| Birth Date: | 11 January 1968 |
| Birth Place: | Tochigi, Japan |
| Position: | Defender |
| Youthyears1: | 1983–1985 |
| Youthclubs1: | Utsunomiya Gakuen High School |
| Youthyears2: | 1986–1987 |
| Youthclubs2: | Kokushikan University |
| Years1: | 1988–1995 |
| Clubs1: | Yokohama Marinos |
| Caps1: | 73 |
| Goals1: | 3 |
| Years2: | 1995–1996 |
| Clubs2: | Yokohama Flügels |
| Caps2: | 31 |
| Goals2: | 0 |
| Years3: | 1997 |
| Clubs3: | Kawasaki Frontale |
| Caps3: | 22 |
| Goals3: | 0 |
| Totalcaps: | 126 |
| Totalgoals: | 3 |
is a former Japanese football player.
Koizumi was born in Tochigi Prefecture on January 11, 1968. After dropped out from Kokushikan University, he joined Nissan Motors (later Yokohama Marinos) in 1988. He debuted in 1990 and he played many matches as center back and defensive midfielder. The club won 1990 JSL Cup, 1991 and 1992 Emperor's Cup. In Asia, the club won 1991–92 and 1992–93 Asian Cup Winners' Cup In 1995, he lost his opportunity to play and moved to rival club in Yokohama, Yokohama Flügels. In 1997, he moved to Japan Football League club Kawasaki Frontale. He retired end of 1997 season.
| Club performance | League | Cup | League Cup | Total | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Season | Club | League | Apps | Goals | Apps | Goals | Apps | Goals | Apps | Goals | |
| Japan | League | Emperor's Cup | J.League Cup | Total | |||||||
| 1988/89 | Nissan Motors | JSL Division 1 | 0 | 0 | 0 | 0 | |||||
| 1989/90 | 0 | 0 | 0 | 0 | 0 | 0 | |||||
| 1990/91 | 19 | 0 | 0 | 0 | 19 | 0 | |||||
| 1991/92 | 10 | 0 | 0 | 0 | 10 | 0 | |||||
| 1992 | Yokohama Marinos | J1 League | colspan="2" | - | 9 | 0 | 9 | 0 | |||
| 1993 | 27 | 2 | 3 | 0 | 2 | 0 | 32 | 2 | |||
| 1994 | 14 | 0 | 0 | 0 | 0 | 0 | 14 | 0 | |||
| 1995 | 3 | 1 | 0 | 0 | colspan="2" | - | 3 | 1 | |||
| 1995 | Yokohama Flügels | J1 League | 15 | 0 | 2 | 0 | colspan="2" | - | 17 | 0 | |
| 1996 | 16 | 0 | 0 | 0 | 5 | 0 | 21 | 0 | |||
| 1997 | Kawasaki Frontale | Football League | 22 | 0 | 0 | 0 | colspan="2" | - | 22 | 0 | |
| Total | 126 | 3 | 5 | 0 | 16 | 0 | 147 | 3 | |||