Secret Garden is one of the names for the rear garden of Changdeokgung palace, so Secret Garden is a part of the palace.

The name, Biwon was shown at Vol. 34 of the annals of King Gojong in 1903. At that time, Biwon was the name of a government office to manage Changdeokgung. In Vol.3 of the annals of King Sunjong in 1908, King Sunjong shot an arrow at Biwon. Based on this record, it is estimated that the Huwon (back garden) of Changdeokgung might be called Biwon around 1904.