| Jidayu Koizumi | |
| Regent: | Imagawa Ujizane (until 1615) Tokugawa Ieyasu (after 1615) |
| Reg-Type: | Lord |
| Era Name: | Shogunate |
| Era Dates: | Tokugawa |
| House: | Uematsu → Koizumi (renamed) |
| House-Type: | Clans |
Jidayu Koizumi (小泉次大夫, 1539 - 1624 January 27) was the Secretary of Water and Hatamoto magistrate of the early Edo period.