Ryakuō (暦応?) was a Japanese era of the Northern Court during the Era of Northern and Southern Courts, lasting from August 1338 to April 1342. The emperor in Kyoto was Emperor Kōmyō (光明天皇 Kōmyō-tennō?). Go-Kōgon's Southern Court rival in Yoshino during this time-frame was Emperor Go-Murakami (後村上天皇 Go-Murakami-tennō?).
During the Meiji period, an Imperial decree dated March 3, 1911 established that the legitimate reigning monarchs of this period were the direct descendants of Emperor Go-Daigo through Emperor Go-Murakami, whose Southern Court (南朝 nanchō?) had been established in exile in Yoshino, near Nara.