Ōan (応安?), also romanized as Ō-an, was a Japanese era name (年号, nengō, lit. year name) of the Northern Court during the Era of Northern and Southern Courts after Jōji and before Eiwa. This period spanned the years from February 1368 through February 1375. The emperors in Kyoto were Emperor Go-Kōgon (後光厳天皇 Go-Kōgon-tennō?) and Emperor Go-En'yū (後円融天皇 Go-En'yū-tennō?) The Southern Court rival in Yoshino during this time-frame was Emperor Chōkei (長慶天皇 Chōkei-tennō?).