| Miyashita Junichi | |
| Fullname: | Miyashita Junichi |
| Strokes: | backstroke |
| Birth Date: | 17 October 1983 |
| Birth Place: | Kagoshima, Kagoshima Prefecture, Japan |
| Height: | 182cm (72inches) |
| Weight: | 72kg (159lb) |
is a Japanese swimmer. He won a bronze medal in the men's 4 × 100 metre medley relay at the 2008 Summer Olympics.