| Kotaro Miyachi | |
| Birth Date: | 18 February 1974 |
| Birth Place: | Fukuyama, Hiroshima, Japan |
| Careerprizemoney: | $44,690 |
| Singlesrecord: | 4–4 |
| Highestsinglesranking: | No. 303 (27 July 1998) |
| Australianopenresult: | Q3 (1999) |
| Medaltemplates-Expand: | yes |
is a Japanese former professional tennis player.
Born in Fukuyama, Miyachi was a World Youth Cup (Junior Davis Cup) representative for Japan in 1990, securing a win over future world number one Marcelo Ríos.
While competing on the professional tour, Miyachi reached a career high singles ranking of 303 in the world. He participated in the qualifying draw of the Australian Open on three occasions. His best performance on the ATP Tour came at the 1995 Japan Open, where he had wins over David Pate and Stephen Noteboom, to make the round of 16.[1]
Miyachi was a singles bronze medalist at the 1995 Summer Universiade.[2]