May 15 has always been called “Teacher’s Day” in Korea, but not anymore. Starting from 2025, this date has been officially recognized as “King Sejong’s Birthday” in honor of King Sejong, one of the most influential figures in Korean history. The official declaration of this day took place in Gyeongbokgung Palace, where King Sejong historically held his royal court. 

Proclaimed the greatest king in Korean history, King Sejong of Joseon is renowned for having created Hangeul, the Korean alphabet, as an alternative writing system for the Hanja, the Chinese alphabet, which was incompatible with the common vernacular. The creation of Hangeul along with other innovative policies during his reign brought upon an era of peace and stability, leading him to be respected by modern Koreans. 

Though celebrating King Sejong’s accomplishments seems quite different from the day’s original purpose of showing gratitude to teachers, the change is not arbitrary. Originally, “Teacher’s Day” in Korea was celebrated annually on May 26, but was changed to May 15 in 1965. Due to his pursuit to educate his people through Hangeul, the Korean government regarded Sejong as “Korea’s teacher,”  purposefully making the day on Sejong’s birthday.  

Although the name of the day has been changed, the purpose of the day ultimately remains the same: honoring and showing gratitude to teachers and advisors in Korea who strive to educate their students.