Kōshō (康正) was a Japanese era name (年号,, nengō,; lit. "year name") after Kyōtoku and before Chōroku. This period started in July 1455 and ended in September 1457. During this time, the emperor was Go-Hanazono-tennō (後花園天皇).

| Kōshō | 1st | 2nd | 3rd |
|---|---|---|---|
| 1455 | 1456 | 1457 |
| Preceded by: Kyōtoku |
Era or nengō: Kōshō |
Succeeded by: Chōroku |